This Week in Bridge
(400) 3rd/5th Best Opening Leads – The Rule of 10/12
© AiB Robert S. Todd
Level: 9 of 10 (5 of 6) robert@advinbridge.com
General
Some partnerships choose to play 3rd or 5th best opening leads, instead of 4th best leads. This is most common against suit contracts. When they do this, they are focusing their opening leads more on count (# of cards in the suit) than on attitude (4th best leads are more attitude oriented). One way this is true is that players who play 3rd/5th best opening leads lead low from xxx (three small) in an unbid suit.
This means that leading a low card no longer promises an honor in the suit, but instead it shows that they do not have a doubleton. Just in case we decide to give these a try, or if we run into another pair that is playing them, we need to know how to interpret these opening leads. Let’s see how we do so.
The Rule of 10/12
When we agree to play 3rd/5th best opening leads (3rd best from 3-card or 4-card suits, 5th best from 5+card suits) then 3rd hand needs a tool to help make use of this information. When we play 4th best opening leads, we have the Rule of 11 to help us. Playing 3rd/5th best opening leads we use the Rule of 10/12 instead of the Rule of 11. When partner is leading 3rd best, there is one additional outstanding card higher than the spot compared to 4th best leads, so we use the Rule of 12. We subtract the spot card led from 12 to know how many cards are in the other three hands higher than the spot – dummy, third hand, declarer. For example, if partner leads the 8 and it is 3rd best then 12-8=4.
If the opening lead is 5th best, the opening leader has four cards higher than their led card. In this case, third hand uses the Rule of 10 to help them determine the layout of the suit around the table. One of the issues with 3rd/5th leads is that third hand player is not sure of the length of the lead – thus not sure whether to use the Rule of 10 or the Rule of 12. Fortunately, this ambiguity is a 2-card one, so we will be more easily able to work out what to do. Let’ see how this works.
Example of Rule 10/12
Imagine partner leads the ♠3 vs. a 4♥ contract and this is what we see:
♠ Q98
♠ 3 ♠ AT72
♠ ??
We use our rules to see that 10–3=7 if it is a 5th best lead or 12-3=9 if it is a 3rd best lead. Since we can see six cards outstanding higher than the 3, then declarer has either one or three cards higher than the 3.
Let’s work our way through this example in detail:
If the 3 is from KJ3, we need to play the T to score our three tricks.
If partner’s lead is from Kx3 (x not the J) then we have two tricks only. It may not matter if we take them now or later (though if we duck, declarer may be able to take their trick and then discard some losers on other suits before we can get our tricks.)
If partner has led from Jx3 then declarer has two tricks – probably best to just take our trick, so it does not disappear.
If partner has led from a 5-card suit, then declarer has a singleton. If it is stiff J or K then we need to take our Ace at trick 1, and if it is a small stiff then we can play the Ten.
We can see that in third hand we do not have a simple decision, but with information from the auction and the 3rd/5th lead analysis we are armed with lots of information to decide how to play at trick 1 – Ace or Ten!
Conclusion
The Rule of 10/12 is used with 3th/5rd best opening leads to help the third hand player make a decision about what to do and how to play the suit. 3rd/5th leads have some advantages and are the common expert treatment but they often create more complexity, as can be seen from our examples. Complexity can be helpful in solving problems for experienced players (the extra information is hopefully useful), but it can be confusing as well. If you are interested, give them a try, but feel free to abandon them if you find them more confusing than helpful -- many players do!