Safety Play: 9 cards missing the QJ

A9xxx opposite KTxx

This is a holding all good bridge players are familiar with and at least think about taking the safety play, but it is something that many somewhat new players may not realize. A priori, the percentage play to take the most tricks in the suit is to play the AK first but only very slightly. This holding most often leads to an application of the rule of restricted choice. When you play one of the high honors and the Q or J drops, it is right to finesse for the other honor if possible. It's also good technique to start by leading low toward one of the honors rather than just lead the big honor first. That way, when second hand is void, you can still pick up the suit for one loser. This play leads to taking all 5tricks 46% of the time and on average yields 4.42 tricks. But 5% of the time, you'll have to lose two tricks (a 4-0 split is 10% but you can pick up one of the 4-0's by leading low and seeing the void in time to adjust and hold it to 1 loser). So, clearly this is the best way to play the suit in matchpoints unless you are in a good contract that you think the field will not get to.

In imps, however, a safety play may be called for. If you need to guarantee that you get 4 tricks in the suit, lead low and finesse either the T or 9 when second hand follows. Still apply the rule of restricted choice when second hand plays an honor. This will yield 4 tricks every time and might get you 5 tricks if second hand is lazy and doesn't split the honors from QJx. So, this is not a safety play to be taken at matchpoints but may have it's place at imps. Here is an example from a hand played today on BBO.

ATx
K
ATxx
KQxxx

KQJ
Axxx
K9xxx
x

In 3NT, on a heart lead, you have 5 major suit tricks and probably need 4 diamond tricks to make the contract. Otherwise the defense will get enough heart tricks to set you (unless the person with the diamonds has the ace of clubs and only 3 hearts, in which case you can afford to lose 2 diamonds after ducking the 2nd round of hearts but not the 3rd). Yes, many if not most people will make it to 3NT but some might get carried away and go down in 6D so giving up a chance to make 4 is probably worth taking a safety play in diamonds. Win trick 1 with the K in dummy and play a diamond to the 9 at trick 2, and you will be rewarded when west shows out.

As a side note, I see many players, even some rather experienced players, who insist on playing to for the drop instead of a finesse holding 10 cards in the suit missing the K. Yes, there is a 13% chance that you will find a singleton K offside but that is the only case that play will win over a finesse while a finesse wins over the drop when there is Kx or Kxx onside. A 2-1 split is 78% and the chance that the 1 is the K is 1/3 of that or 26%. A 3-0 split occurs 22% of the time and playing for the drop will never work so 26+0 = 26%. A finesse is 50%. 50% or 26% - tough choice...