Leads
last update: 23 February 2022
Introduction
The opening lead is very important, some players consider it the most important card played in defence. It can convey so much information, it can set the tone for the whole contract. An ideal opening lead can transmit information on both the distribution (quantity) and quality of the suit.
The leads against suit contracts and No Trumps are fundamentally different. Against a suit contract the first two rounds of a suit can be very important, and it can be vital to take quick tricks before the suit is ruffed. However against No Trumps the aim may be to establish a suit, and part of this process is maintaining communications with Partner. So No Trumps can be a waiting game, and the lead may have an impact on how each of the 13 tricks are played.
The lead often tells Partner (and Declarer) about the distribution in a suit, but it can also help Partner understand the distribution of all the cards in Declarer's hand. A good lead can help set up tricks early, it can lead though honours in Dummy, it can set up a ruff, and even create an extra entry for Partner.
But a blind lead can also give an extra trick to Declarer, and the wrong card can mislead Partner. Players often don't think enough about how the lead will be interpreted by Partner, e.g. a top-of-nothing could mean I don't have an honour, return something else, or it could mean a doubleton and a ruff.
Some experts consider the opening lead the most difficult play in bridge. The auction provides valuable information, and rules concerning leads are only helpful when the information available is limited. Imagine you are sitting West with
♠Q-J-10-6-2 ♥5 ♦K-9-5 ♣9-7-4-2
The uncontested bidding opens with South 2♣ - 2♦ - 2♥ - 3♥ - 3♠ - 4♦ - 6♥. What do you lead? Obviously ♠Q. But South showed control of ♠'s, and North control of ♦'s. Leading away from ♦K against a slam is not a good idea. Can't lead a singleton trump? So it must be a ♣9.
How would you play it? South has three losers, a ♠, a ♣, and a missing K♦. A finesse of the K♦ might work, and if the ♥'s split 2-2 the ♦'s could provide the discards. A ♠ lead would give South the time to discover the 1-3 split in ♥'s, i.e. no access to Dummy with a third ♥, and find the only solution. Play a ♦ and run it to East. Take back the lead and now finesse the K♦, producing two winning ♦'s for discards.
We can see immediately that a ♣ lead is a disaster for South. The message is that there are no obvious leads, no standard leads, that can't be replaced by a little bit of logic (but nothing is 100% certain).
How about this hand with West …
♠A-Q-7 ♥J-5 ♦10-9-8-7 ♣K-6-5-3
The Opponents, South opened 3♠ and North raised to 4♠, Partner East doubled. South should be holding ♠K-J-10-x-x-x-x, so A-Q-x are two winners. Was East's double for ♥? Why guess? Play ♠A, see the Dummy, and Partner East may be able to signal.
What is outlined below are less rules than guidelines, and they will help when there is little or no information available.
But there is no substitute for listening to the bidding. Have a look at the end of this page for some test questions.
I'm going to start with the leads recorded on a typical World Bridge Federation (WBF) Standard System Card or "cheat sheet". It's just one example, but it's a good place to start.
Opening Lead is the first card played after the contract has been decided. The aim can be to rapidly take winner, to develop winners in hand, or to lead a suit bid by Partner.
Options are:-
Against suit contract - 3rd/5th
Against NT - 4th
Other - 2nd from 4 small
Analysis - Lead Partners suit has the status of a general rule, even if occasionally "some rules are made to be broken". This is often a test of a partnerships mutual understanding. A Partner might expect a lead in their suit, and a good Partner will think twice if that does not happen, e.g. the lead might be singleton, etc. Further down this webpage we will look at which card to lead in Partners suit. A classic lead in Partners suit is the Ace from A-x, but from A-x-x or A-x-x-x it would be a subject of the partnership agreement and possibly indicated on the System Card. An alternative lead might be a singleton in another suit (in particular when sitting with A-x, A-x-x or K-x-x in trumps). Or Ace from A-K-Q… or A-K… in another suit. Or K from K-Q-J… Another alternative is to lead trumps if there are indications that Declarer is weak or might need ruffs, etc. So leading partner suit should be 'obvious', it should be the best option after careful consideration.
For example, it's important to know if Partner opened, or overcalled Opponents, or made a 'lead directing' double (an artificial bid). It's also important when Partners' bid has received support, or if Opponents have cue bid that suit (possibly suggesting a control or singleton/void).
As a very specific example, Partner might have overcalled an opening 1♣ with 1♥, but Opponents are now playing 3NT. What to lead from ♥J-6-3? Firstly, just how many points is the Partner likely to have? Secondly, is Partner likely to overcall with something like ♥K-9-8-5-2, or does Partner only overcall with a robust suit ♥K-Q-8-5-2 or ♥A-Q-8-5-2? In the first case leading the ♥J might make life much easier for Declarer who is holding ♥A-Q-10, the ♥3 might be better. In the second case the ♥J would be a perfect lead. Of course, the bidding might indicate that Dummy is holding a protected ♥ honour, so again the ♥J might be the ideal lead.
Analysis - Third and fifth card opening leads were originally designed for four or five card suits, respectively. From a four card suit, the third highest card is led. From a five card suit (or longer), the fifth highest card is led.
Alternatively, many Players use third and fifth leads from an even or odd number of cards, respectively. A opening lead of the third highest card would be from an even number of cards in a suit, and the fifth highest card from an odd number of cards. The difference between the original practice is subtle, e.g. from a six card suit, the third highest card is led instead of the fifth highest card.
The benefit of third and fifth leads is that they help Partner gauge suit length. Playing standard leads, the 2 would be led from both K-9-2 and K-9-7-2. Playing third and fifth however, the lead of a 2 always indicates a three or five card suit. It's easier for partner to guess whether their partner is holding three or five cards in the suit, rather than whether they are holding three or four. A disadvantage of third and fifth leads is that the third highest card is sometimes too costly to lead. For example, leading the 9 from K-J-9-2 can easily be a mistake.
Third and fifth leads are used in conjunction with the Rule of 10 and the Rule of 12. These algorithms are used by the Partner to count how many higher cards Declarer has in that suit. But they can also be used by Declarer to determine the holdings in the Right-Hand Opponent.
Rule of 10
The Rule of 10 is used when a lead is fifth-best. It works as follows:-
Subtract the opening lead spot card from 10.
Also subtract the number of cards in Dummy that are higher than the card led.
Finally, subtract the number of cards in your hand that are higher than the card led.
The final number equals how many higher cards Declarer holds in the suit.
Rule of 12
The Rule of 12 is used when a lead is third-best. It works as follows:-
Subtract the opening lead spot card from 12.
Also subtract the number of cards in Dummy that are higher than the card led.
Finally, subtract the number of cards in your hand that are higher than the card led.
The final number equals how many higher cards Declarer holds in the suit.
Test: Partner leads ♥5 from what you think might be a 5-card suit. You are holding ♥K-J-2, and the Dummy shows up with ♥10-9-6. How many ♥'s does Declarer have that are higher than the ♥5? The answer is 2.
Test: Leading the 10 from K-J-10-x(-x) is an example of the lead of the 3rd card (also valid for A-J-10-x). However, it is also an example of what is called a "Coded Nines and Tens". This opening lead system is designed to show honour holdings. A lead of a 9 or 10 implies either zero or two higher honours in the suit led. The lead of the 9 would imply a hand with a 10 and an honour, e.g. K-10-9-x, Q-10-9-x, A-10-9-x-x. Leading a Jack suggests no higher honours, but a sequence J-10-x-x minimum. Normal "low from honour" lead carding still applies, as does the 4th best, etc. When Partner leads a 10, it will be assumed that they have 2 cards above, unless the Dummy or Declarer invalidated that conclusion. When Partner leads a 9 and a 10 is visible, the conclusion is also invalidated. A special case is the lead of the 9 from A-K-10-9-x or A-Q-10-9-x, because the lead of the 10 might suggest K-J, and the 9 will ensure than Partner knows that there are two honours waiting for them. Given that a lead of the 9 implies the 10, with a hand such as A-Q-9-3-2 the lead must be 3 against NT. Also with Q-J-9-x the best lead would be Q, not 9. So remember, a lead of a 10 or a 9, when the other card is visible, means no honours. These leads are typical for NT contracts.
Analysis - Fourth card opening leads against No Trumps, from the longest and strongest suit. Partner to use the Rule of 11 to find out how many higher cards than the opening lead are in the other three hands. Usually, Partner will expect an honour or two at the top of that suit. This is a 'traditional' lead, but it's not an obligation, and there are numerous situations when the 4th card in a suit is not the best option.
Rule of 11
The Rule of 11 is used when a lead is fourth-best. It works as follows:-
Subtract the opening lead spot card from 11.
Also subtract the number of cards in Dummy that are higher than the card led.
Finally, subtract the number of cards in your hand that are higher than the card led.
The final number equals how many higher cards Declarer holds in the suit.
This rule can also be used by Declarer to determine the holdings in the Right-Hand Opponent.
Analysis: Leading the 2nd card from 4 small cards, appears to be from a general rule to lead the 2nd highest from three or more small cards, and appears to be linked the so-called MUD for playing card in the order middle-up-down. The idea is that it may be possible to determine if the lead came from an honour or not. Interestingly Declarer might not be able to decide if this card is the 2nd card from 4 small cards or a small card from an honour, whilst Partner will have a better chance to work that out (in particular if they are holding the honour). An alternative might be 'top-of-nothing' but that might also mistakenly suggest a doubleton. Leading 2nd highest from four small cards will probably not confuse Partner into thinking it's a doubleton.
Remember, with the lead, Partner will immediately try to figure out where they can cause the biggest problem for Declarer. The wrong card, creating a wrong interpretation with Partner, can change drastically the outcome of the contract. False carding from Partner or Declarer can add to the confusion.
Which card to lead is listed under Preferred Leads on the Standard System Card of the WBF, and on our example is as follows.
In No Trump contracts (preferred card)
A-K, A-K-x-(x…) - asking for 'attitude'
K-Q, A-K-J-10-(x…), K-Q-10-9-(x…) - asking to unblock or count
Q-J, Q-J-x-(x…), A-Q-J-x-(x…), K-Q-x-(x…)
J-10, J-10-x-(x…), A-J-10-x-(x…), K-J-10-x-(x…)
10-9, or honour-10-9-(x…)
9-8-x-(x…)
(Hi-x) x-x, x-x-x, x-x-x-x (a high card can be a even number)
(Lo-x) honour-x-x, honour-x-x-x (a low card can be an odd number)
In suit contracts
A-K-x, A-x-x-x-(x…)
K-Q, K-Q-10-9-(x…)
Q-J, Q-J-x-(x…)
J-10, J-10-x-(x…), K-J-10-x-(x…)
10-9, 10-9-x-(x…), honour-10-9-x-(x…), 10-x
9-x, 9-8-x-(x…)
(Hi-x) x-x, x-x-x, x-x-x-x-(x…) (high card even number)
(Lo-x) honour-x-x, honour-x-x-x-(x…) (low card odd number)
It looks as if some are 'traditional' lead options, e.g. top of a sequence (J-10-x or with split honours K-J-10-x), smallest from K-x-x or Q-x-x, top of a doubleton, and avoiding leads from holding such as A-Q-x or K-10-x.
Above we used the Standard System Card of the WBF as a way to introduce the topic of leads. There are three aspects to leads. Firstly, what type of leads are possible? Secondly, how to decided which one is the most appropriate? Thirdly, which card to play?
Improving on the opening lead, even by a small amount, will see the biggest improvement in a Players game. Over thousands of hands there was a 14% different between someone who always made the worst lead and someone who always made the best lead (fortunately no one is that unlucky or lucky). In a recent analysis of the worlds best pairs, they gave up a trick on the lead in almost 20% of the hands.
We will now try to look at each type of lead, but some of below comments won't always match what was shown in the above Standard System Card example. There will also be an element of repetition.
Types of Leads - Lead partners suit
Lead Partner’s suit, especially to a promised five or six cards. The proper card to lead is the same as would have been led in any other suit. Therefore, lead low from Q63 or K852, this is called BOS "bottom of something". Some players lead the top of a suit if Partner has bid the suit. The approach adopted requires an agreement with Partner. Lead top of a three-card (or longer) sequence, or lead "top-of-nothing". One modern problem is that overcalls can be very aggressive, so there is not guarantee that Partner is holding a good suit. Much has to do with knowing if partner overcalls with Q-10-9-x-x or always with a solid K-Q-x-x-x or A-Q-x-x-x, e.g. leading an A-x-x or K-x-x will depend on this (but A-x remains a very effective lead). Some experts suggest leading small A-x-x or K-x-x to Partners suit.
Leads to Partner can be against a suit contract or No Trumps. Starting with a suit contract:-
Top of a doubleton, e.g. A-x, 9-6, K-7, J-2
Top of touching honours, e.g. Q-J-5, 10-9-3, J-10-7
Low from 3- or 4-card with honour, e.g. Q-7-4, A-3-2, K-8-4-3, J-5-4-2
'Top of nothing', e.g. 9-7-4, 6-3-2, 9-8-4-3, 7-5-4-2
Leads to Partner against a No Trump contract:-
Ace, e.g. A-7-5, A-J-10-6
Top of a doubleton, e.g. 9-6, K-7, J-2
Top of touching honours, e.g. Q-J-5, 10-9-3, J-10-7
Low from 3- or 4-card with honour, e.g. Q-7-4, A-3-2, K-8-4-3, J-5-4-2
You raised Partner - lead high, e.g. 9-7-4, 7-5-4-2
You did not raise Partner - lead low, e.g. 9-7-4, 7-5-4-2
There are times when leading Partner's suit is not the most profitable route, e.g. Opponents have shown a potential void (splinter, strong overcall) and therefore probably also have a good side suit. The key might be to find Opponents weaker side suit. Opponents who have bid a slam despite an overcall by Partner know they control that suit, so try a different lead. One the other hand, if Partner opened (showing HCP's and shape) leading to their strength would probably be the best option.
A special case is when Opponents have bid NT over Partners 5-card major intervention. There may be a 'killer lead' in a side suit, but a different lead could provide overtricks to Opponents. Often it is better to settle for an 'average' than risk a 'zero'. Helping Partner might be the only safe option, and one that will probably be taken at most of the other tables.
Types of Leads - Sure tricks
Against suit contracts lead - A-K, A-K-5, A-K-Q, A-K-Q-7Types of Leads - Top of a sequence
Against suit contracts lead 2-card (+) sequence - A-K-9-7, Q-J-8-4, K-J-10-9Against No Trump contracts lead 3-card (broken) sequence - A-K-Q-7, Q-J-10-3, Q-10-9-8-3
It is better to lead top of a sequence than 4th-best (or 3rd and 5th against a suit contract), but the sequence must contain an honour (10 or higher).
Against a suit contract, a sequence can be as short as two cards. Lead the K from K-Q-5-3 and Q from Q-J-6-4. However, against a No Trump contract, lead low from both holdings.
Types of Leads - Lead from length
What to do if Partner did not bid, and the hand does not contain a sequence? Prefer to lead a suit the Opponents have not shown. In general, try to lead from length against any contract. Lead from the longer suit is more attractive. It is acceptable to lead away from a King against a suit contract.
Types of Leads - Lead dummy's suit
Leading through strength is overrated. Lead Dummy’s suit only when Partner is likely to have length and strength behind the Dummy.
Types of Leads - Lead a trump
It is usually best to find a more aggressive lead, but there are times when a trump lead is the only safe option.
Against the bidding 1♠ - 2♠ - 4♠, what to lead from…
♠6-4 ♥A-J-9-3 ♦A-Q-10-5 ♣K-J-6
Since leading a side suit is unattractive, lead a trump.
In the sequence 1♠ - 1NT - 2♠, a trump lead must be considered. Dummy has denied support for a major suit opener. Dummy obviously has 0, 1, or 2 card support for ♠. A trump lead could be very effective.
Types of Leads - Lead from a suit that includes an Ace
Never under lead an Ace against a suit contract at trick one.
Reasons to lead an Ace:-
Without King, lead the Ace only when defending against a slam (except 6NT)
If Declarer preempted
If the Ace is singleton
If the Ace is in the only unbid suit against a five ♣ or five ♦ contract
If Partner promised length and strength in the suit
With a seven- or eight-card suit.
Types of Leads - Lead a short suit
Against suit contracts lead singleton or top of doubleton - A, J, 9-4, 8-6 with trumps
Singletons are invariably good choices, but leads from doubletons are overrated, especially with one honour. The best time to lead a short suit is when also holding trump control, e.g. A-6-3.
Avoid leading from a short-suit when a ruff is not needed, e.g., with trump holdings such as QJ9 and KQ10 or with trump length. With four trumps it is usually correct to lead a long suit to make Declarer ruff.
Types of Leads - Leading against No Trumps
The 'tradition' lead is 4th highest of the longest, strongest suit. This is probably the best lead against Opponents who have simply bid NT (e.g. 1NT - 2NT or 1NT - 2NT - 3NT) or used Stayman before ending in NT.
Length (5-card) is usually more important than strength, e.g. prefer ♥J-9-x-x-x to ♦A-K-x-x. Leading 4th from a good 4-card suit is a poor option (e.g. K-10-5-3) as compared to Q-8-3-2.
Starting with the top of a 3-card sequence is an excellent option, e.g. K-Q-J, Q-J-10-x or K-J-10-9-x (leading from a 2-card sequence against NT is often a poor option).
Many players will start with the '2nd from rubbish', e.g. 9-8-6-5-3 (with 10-7-5-3-2 the 7 or 3 are both valid), and follow next with the lowest (e.g. with 9-7-3-2 lead 7 then play 2). Better lead a worthless major than a worthless minor.
Leading top of a doubleton major against NT is a good option, e.g. 9-x or K-x since Partner will always have at least a 4-card suit. From a 3-card major suit lead MUD, and lead 3rd from Q-x-x and 4th from K-x-x-x.
Success in NT is often based upon an even
Types of Leads - Against a Preempt Opening
An opening Preempt starts at the 2-level with 6+ cards, and usually no more than 10 HCP's.
Honours are usually concentrated in the long suit, and there can sometimes be a 4-card outside suit.
Potential distributions are 6-3-2-2, 6-3-3-1, 6-4-2-1, 6-4-3-0, 7-2-2-2, …
Declarer's losers will probably be in the (short) side suits.
The aim in Defence is to quickly take the maximum number of tricks in the side suits, and in particular in the 3-card side suit. If the Defence has a long suit, Declarer in likely to have a short in the same suit. Leading the 4th of a 4-card or 4-card suit could be leading into Declarers' short suit. Best is to lead from a 3-card or 4-card suit, ideally touching honours, e.g. better K-Q-J than K-Q-x-x-x. Leading into A-Q in a side suit of a Preempt is unlikely, so a K-x-x is not to be ruled out.
Leading a trump against a Preempt should not be ruled out, the stronger the hand the better the trump lead.
An Ace lead from strong hand can be useful to "see" the dummy.
Leads will be different in a Preempt and a Preempt converted into game by Partner.
What card to lead against a suit contract?
Top of a sequences (two or more cards)
2-cards - A-K
3-cards - A-K-x, A-K-Q, K-Q-x, Q-J-x, J-10-x, 10-9-x
4-cards - A-K-Q- 7, A-K-9-4, K-J-10-x, K-10-9-x, K-Q-10-9, Q-J-8-4,… 10-9-8-x
5-cards - K-J-10-5-4
High cards
2-cards - A-x, Q-x, J-x, 8-x, x-x (best avoid leading an honour from a doubleton)
3-cards - A-x-x, A-J-x, A-10-x (do not lead from an A-Q-x)
4-cards - A-K-10-x, A-K-x-x, A-J-x-x, A-10-x-x, A-x-x-x
4-cards - A-K-J-x, A-K-10-9, K-Q-x-x,
Do not lead from A-Q-J-x or A-J-10-x
Do not lead from K-J-x, K-10-x, Q-10-x, K-x-x, Q-x-x, J-x-x, 10-x-x
Honour-x-x or Honour-x-x-x lowest card shows an honour, e.g. K-7-4, J-9-2
Without high cards
1-card - A, J, 6 (only with trumps in hand)
2-cards - 9-4, 8-6 (high-low)
3-cards - x-x-x (MUD)
4-cards - x-x-x-x (high-low = even number)
5-cards - x-x-x-x-x (low-high = odd number)
6-cards - x-x-x-x-x-x (high-low = even number)
Avoid leading 4th best against a suit contract, although some experts advise to also lead 4th highest, e.g. K-J-7-5-3
Lead a trump
Do not under lead an Ace
Do not lead and singleton King
Some advise not to lead from honour doubleton, e.g. A-x,… J-x
What card to lead against a No Trump contract?
Length lead - 4th best, e.g. Q-10-8-4, K-J-7-5-3, A-K-9-4
Top of a sequences, where some Players use the same requirements as for a suit contract, whilst others prefer a 3-card (broken) sequence, e.g. A-K-Q-7, Q-10-9-8-3
3-cards - A-K-x, K-Q-x, Q-J-x, J-10-x, 10-9-x
4-cards - K-J-10-x, K-10-9-x, K-Q-10-9, … 10-9-8-x
5-cards - K-J-10-5-4
Special requests
A-K-x-x-(x) - against NT, King asks for 'attitude' (e.g. high-like, low-dislike)
A-K-J-x-(x) - against NT, Ace asks to unblock honour, if no honour give count
Without high cards
2-cards - x-x (high-low)
x-x-x, x-x-x-x, x-x-x-x-x,… (MUD)
Avoid leading 4th highest from A-x-x-x, A-Q-x-x, A-j-x-x, K-J-x-x, but can lead 4th highest from A-Q-x-x-x and A-J-x-x-x
We mentioned in the introduction "Coded Nines and Tens" against No Trump contracts. They are also called one of the Journalist Leads, the "Ten Promises and Jack Denies". This means that an opening lead of a 10 promises an honour (Ace, King or Queen) and an interior sequence 10-9 or better. On the other hand the lead of a Jack denies an honour, but should top of a sequence. One associated argument is that a Queen is never led from Q-x because it could be misinterpreted. The implication is that with 10-9-8-x or 10-9-x-x the 10 cannot be led.
Have a look at this hand… Opponents are in 3NT, and partner leads ♣J. Dummy is…
♠8-6 ♥A-Q-J ♦A-K-Q-10-7-4 ♣9-2
You are holding ♠Q-J-10-4 ♥10-8-6-5 ♦5-3 ♣A-5-3, what do you do? With the ♦'s you only have really one chance, but you might guess that partner is holding 5-7 HCP's. You have to assume that it's not the ♥K, perhaps ♠A, or could the ♣J be part of ♣K-J-10-x-(x) or is it just J-10-x-x-(x)? You could defeat the contract with a return of a ♣ or ♠Q. With a 'standard lead' it is impossible to know, but with a 'strong 10' or "Ten Promises and Jack Denies" you would know that a lead of a 10 promises K-J-10-x-(x) or A-J-10-x-(x), and the lead of a J just means J-10-… Easy!
Coded 7's, 8's and 9's
Many players will lead 4th best against NT, or third or fifth against a suit contract. This tells Partner the distribution in the suit, but it also helps Declarer. Better to use a coded 9 or 10 against both suit and NT contracts, and combine with second highest from worthless hand (called Roman Mud). So J denies and 10 or 9 shows two or zero honours. A really low card means you like the suit and have an honour with 4- or 5-cards, e.g. from K-8-7-5-2 lead 2, and from Q-8-7-2 lead 7, but from 10-6-5-3 lead 6, and from J-9-8-2 lead 8, because 9 would imply zero or two honours. Coded 9 or 10 is often played against NT, but can also be used against a suit contract. For example, from 7-5-2 play MUD informing Partner it's not a doubleton, a 2 would suggest an honour, and from a 5-3-2 the lead of a 5 would be more difficult to interpret by Declarer than Partner. There are also coded 7's, 8's and 9's, where the lead of a seven is a singleton, and the coded 8 or 9 can be used in the same way as a code 9 or 10. This must be marked on the System Card as 'Special Carding'.
Summary
Leads Against Suit Contracts
You usually want to make a "safe" opening lead that will set up tricks for your side without giving declarer extra tricks. Your general order of preference could be:-
A suit partner has bid (or is implied by a takeout request or lead directing double). If you have supported partners suit lead top-of-nothing, or top of touching honours, or low from a 3 card honour, or the Ace if you have it. If you did not support partners suit lead low if you have 3 cards but not if you hold the Ace, or lead high from 2 cards, or top of sequence of honours.
A suit that offers a good attacking combination, e.g. the top of two or more touching honours (K-Q-10-x, Q-J-10, A-K-x-x, J-10-9), in particular if suit is short. Remember a K promises A, a Q denies a K but promises J.
A singleton is always a good lead if opponents did not bid that suit (if you can ruff but do not have an honour trump, hoping partner can lead the suit back for you to trump).
Long powerful non-trump suit, forcing opponents to exhaust trumps (very useful if you hold 4+ trumps, if opponents have a two suit hand or if opponents have only a 4-3 fit in trumps).
Your longest suit. Lead low if you don't have touching honours.
A suit the opponents have not bid.
If there are no unbid suits, choose a suit that dummy has bid.
Lead trumps if you have no other safe lead, or if declarer has shown a two-suited hand. This may prevent declarer from using dummy's trumps to ruff or cross-ruff.
Lead trumps if partner has passed, converting your takeout double to a penalty.
Lead an Ace against preempts if you have one.
Ace from a doubleton.
Leading an Ace can come from A-K-x-(x), A-K-Q-x, A-K-Q-x and is always asking Partner for a 'attitude' (e.g. high-like, low-dislike)
When the opponents have bid their suit aggressively, it is time to be passive, e.g. top-of-nothing. This is useful if opponents on minimum points or do not have a good side suit or if declarer is strong but dummy weak or with a poor fit. It's also useful if you have all the points and you don’t expect support from partner.
When the opponents are in a major suit contract, lead the other major unless you have a decent alternative in a minor suit.
When you have a choice between two suits, lead the one with the strongest secondary cards.
When you have a weak defensive hand lead an unsupported honour in partner’s suit.
If game came from an invitation (e.g. 1♥ - 1NT - 3♥ - 4♥ or 1♥ - 2♥ - 3♥ - 4♥) it may be better to play passive, often a trump from x-x-x.
If trumps are going to break badly for Declarer, or trump combinations are good for the defence (e.g. K-J-x, A-Q-x, Q-x-x) it may be better to play passive.
If Declarer clearly has the abundant points and good trumps, an aggressive play may be better, but also it may be sensible to take the top tricks when possible (e.g. leaving game to Opponents is better than gifting them overtricks).
If opponents have outbid you (e.g. 5♥ over 4♠) is is probably a sacrifice, and they will look for ruffs, so lead trumps.
Avoid leading trumps if possible.
Avoid lead Partner’s suit if your support is poor or you have trump control.
Avoid leading a singleton if there is a better option.
Avoid leading a suit bid by Declarer (unless its trumps).
Avoid leading a long suit if bid by opponents (except if partner may ruff).
Avoid leading from 2-card suit (doubleton), because a ruff will be rare, and there are usually better options.
Avoid leading a singleton trump (unless Partner has a long trump and has passed on a takeout double, or opponents have made a high-level sacrifice with few honours, and are planning to cross-ruff).
Avoid leading an unsupported Ace if there is a safe lead available.
Avoid leading from broken honours, and don't under-leading broken honour combinations (K-J-x-x, Q-10-x), unless it's Partner's suit.
Avoid leading an unsupported Ace.
Avoid leading an Ace in your suit, even if Partner supported it (its costs trick more than it wins one).
Never under-lead an Ace, unless it's A-x-x in Partners suit, and you know Partner will be holding the King
Avoid under-leading a King.
Avoid leading a suit that Partner could have bid, but refused to do so.
Leading Against Slam Contracts
King from touching honours, e.g. K-Q-…, A-K-… (important Parent should give count signal)
Ace (not if opponents may be void)
Make passive lead if slam looks likely
Leads Against No Trump Contracts
You usually want to make an attacking opening lead to set up tricks in your long suit, namely:-
Lead Partner suit (or takeout request or lead directing double). Lead Partner’s suit, even if you have a good 5-card suit as an alternative, unless you also have an outside entry. Always ask the question why lead Partners suit? Surely Declarer has clearly indicated with 3NT that they don't fear it.
Lead the 4th-best card from the longest and strongest suit, with good intermediaries. Leading from the longest, strongest suit stops Partner having to guess (and Declarer as well).
Leading an Ace can come from A-K-x-(x), A-K-Q-x, A-K-Q-x, A-x-x, A-x and is always asking Partner for a 'attitude' (e.g. high-like, low-dislike)
Lead your long suit if it has three or more touching honours (K-Q-J-x, Q-J-10-x, A-Q-J-10-x, J-10-9-x, etc.). You should lead an honour to be sure you force declarer to win with the highest card possible.
The top of two or more touching honours in a 4+ suit (K-Q-10-x, A-K-x-x, J-10-x-x, and Q with A-Q-J-x), but not a 4 card suit with only 1 honour or 2 intermediate honours.
Often a K is asking Partner to unblock, i.e. holding A-K-J-x, K-Q-10-x, K-Q-J-x, K-Q-x
Your longest unbid suit (5+ cards) with useful entries and an honour in suit.
A suit dummy has bid, in particular a 4-card major refused by Opener.
Without useful entries in your long suit, lead another suit helpful to partner, e.g. unbid major if possible.
Lead the unbid suit in No Trump (or a suit contract) if the Opponents reached the contract slowly.
Against a "gambling" 3 No Trumps, lead an Ace.
When you have a choice between two suits, lead the one with the strongest secondary cards.
When the opponents have bid their suit aggressively, it is time to be passive.
When you have a weak defensive hand lead an unsupported honour in partner’s suit.
Against 1NT - 3NT, even with a long minor, lead a major.
Against 1NT - 3NT, with a 4-3 in majors, lead the shortest, with 4-1 in majors, lead the singleton.
With a voice of two equal length suits, lead the one without the Ace, it can be an entry later.
If game came from an invitation (e.g. 1NT - 2NT - 3NT), it may be better to play passive.
Avoid leading an unbid suit when the Opponents have jumped to game.
Avoid leading from J-x-x-(x), more often than not it costs a trick.
Avoid leading a short suit, unless it's the suit partner has bid.
Avoid leading 4th best with a weak hand or a suit with bad intermediates.
Avoid leading Aces or "unprotected" high cards, especially ones in your short suits.
Avoid leading a suit declarer has bid.
Avoid leading from broken honours.
Avoid leading from x-x-x or x-x-x-x-(x) because it can exposes Partner to a finesse.
Avoid leading a long suit if you don’t have entries to your hand.
Avoid under-leading a King.
Questions
Test 1: ♠Q-10-5 ♥K-Q-8-5-3 ♦K-8-3 ♣8-2
Test 2: ♠9-5-3 ♥Q-5-3 ♦7-6-2 ♣J-8-4-2
Test 3: ♠Q-J-9-7-6 ♥K-5 ♦J-7-6-3-2 ♣7
Test 4: ♠A-Q-9-7 ♥A-Q-5-4 ♦10-9-8-7 ♣7
Test 5: ♠7-3 ♥A-5-4 ♦Q-10-8-7 ♣Q-7-5-3
Test 6: ♠5-3-2 ♥A-Q-7-5-4 ♦Q-J-10-3 ♣Q
Test 7: ♠9-7-3 ♥K-4 ♦8-7-6-5-4-3 ♣K-7
Test 8: ♠9-7-2 ♥A-J-10-9-4 ♦7-6 ♣5-4-3
Test 9: ♠Q-9-7 ♥A-J-7 ♦K-J-2 ♣8-7-6-3
Test 10: ♠A-2 ♥A-5-3 ♦A-7-6 ♣6-5-4-3-2
The bidding was 1NT - 3NT. Your lead!
Answers
Test 1: Lead the 4th best of best suit, ♥5
Test 2: Weak hand, look to find Partner in a major, lead ♥3
Test 3: ♠Q is better than 4th best
Test 4: Avoid the majors, lead a code ♦10 indicating two honour or no honours
Test 5: Two 4-card minors, lead ♦7
Test 6: Lead the 4th best of best suit, ♥5
Test 7: Two weak suits ♠ and a useless ♦, lead ♠9
Test 8: Lead ♥10 showing two honours or no honours
Test 9: Great hand, tell partner ♣ are weak, with a top of nothing ♣8
Test 10: With three entries lead ♣6.
The Opponents bidding was 1♦ - 1♠ - 3♦ - 3NT, and you have
♠J-9-8-7 ♥8-5-3 ♦J-8-3 ♣A-7-5
What do you lead? Opener has a strong ♦ suit, and Dummy has ♠. Partner did not overcall 1♦, suggesting that a ♥ lead would not be effective (unlikely 1st or 2nd round control). So, it's ♣'s. Partner could have 7-8 HCP's. Try the ♣5. A Pass is also an informative declaration.
The Opponents bidding was 1♠ - 1NT - 3♥ - 3NT, and you have
♠A-7 ♥10-9-8 ♦J-7-5-4 ♣J-6-5-4
What do you lead? South did not bid a minor, nor support Declarers majors. Looks like Declarer has 2 4-card minors, and a 2♠ and 3♥ in majors. Leading a minor from J-x-x-x is not a successful lead in No Trumps, so it's either ♥10 or ♠A.
You have ♠K-J-7-2 ♥8-6-3 ♦J-10-9-5 ♣A-3, what do you lead after the following three auctions?
1♥ - 2♥ - 3♥ - 4♥ - lead ♥, safe and might reduce ruffing
1♣ - 1♥ - 2♣ - 3♥ - 4♥ - they have a potentially good second suit in ♣'s, lead aggressive with ♠2
1♥ - 2NT - 4♥ - lead ♦J, safe and could produce a trick
Three examples about determining Declarer's intentions from the bidding, then leading accordingly.
1♠ - 1NT - 3♥ - 4♥ - suggests that Declarer will look to trump ♠'s in Dummy, lead trumps
1♠ - 3♦ - 3♠ - 4♠ - Declarer will try to draw trumps and use Dummy's long ♦'s, lead ♣'s or ♥'s
Here we have the Opponents bidding 1♠ - 3♠ - 4♠, and you must lead from
♠9-4 ♥9-5 ♦A-9-7-6-2 ♣J-7-5-4
What would your lead? To understand the following analysis we need to introduce MP and IMP. Match Points (MP) are all about scoring more than other pairs who have played the same hand. A pair scores 2 MP for every other pair who plays the same hand and who scores less (fewer points), and the pair scores 1 MP for every pair who score the same. Scores are added across the collection of boards played, and usually expressed as a percentage. In theory a pair that score the absolute best on each hand, would score 100%, but 60% to 65% would usually be considered a very competitive score. International Match Points (IMP) is the difference (the 'swing') in total points scored between two different pairs. The difference in points is converted into IMP's, and one version involves comparing a pairs score against every other pair who played the hands. These are then summed, and possible averaged, for all the hands played. This bidding sequence and this hand were fixed, but the remaining hands were simulated 5000 times (so-called double dummy), always hands that would produce the same declaration. It showed that the lead of ♥9 had the highest chance of beating the contract (17.6%) at MP, but it was the lead of the ♦A that created the highest number of tricks for the defence 2.61 IMP. This difference was not intuitive, but is because the defence retains the lead with the ♦A, can see the Dummy, and lead a more effective next card.
Here we have a competitive auction (with East-West in brackets) 1♠ - (1♥) - 2♠ - (3♥) - 3♠ - all pass. What do you lead with this hand…
♠J ♥A-Q-10-7-2 ♦J-6-3-2 ♣A-4-3
The lead of the ♦2 or ♦3 had a 40% chance of defeating the contract (MP) and the highest IMP at 4.26. The lead of the ♥A was the least successful, as might be expected. What the simulation found was that leading from a Jack is not as dangerous as experts believed (leading from an unsupported Q or K remains a poor choice).
Other results from the same work that may contradict existing practices include:-
Leading an unsupported ace works much better than textbooks suggest. These leads very often rank 1st.
In NT leading from touching honour, e.g. K-Q-x-x-(x) or Q-J-x-x-(x) works better than the usual 4th best lead.
Doubleton and singleton leads also work better than textbooks suggest. The danger of helping declarer set up a side suit is overrated.
Aggressive leads from K-x-x or Q-x-x are very likely to cost a trick.
Leads from J-x-x are almost as safe as leading from x-x-x and should be preferred to leads from honour-x-x.
Agressive or Passive
Throughout this text there has been a constant theme, should the opening lead be aggressive or passive. Try to identify the contract as being light on HCP's, of sufficient strength, of above average strength, or of unspecified strength.
2♥ - (Double) - 4♥ - (Double) - suggests they lack HCP's, and can only be successful with a favourable distribution
1NT - 2NT - 3NT - they probably have about 25 HCP's, which is enough with 'typical' distribution
1♣ - 2♣ (inverted minor) - 3♥ (+18 HCP and 3♥) - 3NT - at least 29 HCP, so only a very bad distribution will affect them
1NT - 3NT - could be anything between 23 and 31 HCP.
Selecting an opening lead should reflect the above analysis, is there an indication about the type of distribution. Will it be favourable, average, or bad for Declarer? How are the remaining points distributed in defence. A weak Partner can make a bold opening lead, whilst a Partner with a stronger hand might best prefer a passive lead. What is the probability of establishing or losing a trick in each suit? Will the loss of a trick affect the outcome?
Try to image how the card might be distributed. Image what Declarers plan might be. Given the likely distribution and location of honours, are the breaks favourable or unfavourable to the defence? For a particular lead, what the chance of establishing or losing a trick? On some hands it won't make much difference, but on others it could be really significant.
The more the Opponents bid, the more information becomes available, the more important it is to exploit those clues to build a picture of the hands and anticipate Declarers plan. However if the bidding is short and sweet, then it will depend much on how asymmetric is the distribution and where the honour cards are place. The opening lead will be all about establishing or losing a trick in the suit, and that will be down to experience.
References
A Complete Bridge Leads Course
Always Lead Partner's Suit
Leads in Partner's Suit
Opening Leads
Opening Leads and Signals
Opening Leads into Preemptive Opening Bids
https://kwbridge.com/bb/leads1.htm
https://kwbridge.com/bb/leads2.htm
https://www.bridgehands.com/C/Coded_9_and_10_Jack_Denies_10_Implies.htm
https://www.bridgebase.com/forums/topic/74741-leading-from-small-cards/
http://www.rpbridge.net/1u29.htm
https://en.wikipedia.org/wiki/Contract_bridge_probabilities