A card combination

[Antrax]

With QJ seventh opposite a singleton in dummy, i.e. missing AKTxx in the suit, you lead from dummy and your right hand opponent follows small. Is it better to play Q and later J, hoping the T is a doubleton, or is it better to finesse? Does it boil down to just whether there's more than a 50% chance of the T being doubleton on my right, or is the added information from RHO's play helpful in any way?

[chasetb]

Suitplay says missing the AKT98, always finesse the Q or J. Missing the AKT9x, you should still finesse for MAX tricks, but you can choose between finessing and hoping to drop a singleton A or K. Missing the AKT62, again finessing produces MAX, but either finessing against the 6 or ducking guarantees 4 tricks.

 

I can't help much more than that, but I do recommend downloading suitplay - www.suitplay.com

[Antrax]

The problem with suitplay is that I can't use it at the table :) There's probably a way to think about these things that simplifies them. I hope.

[nigel_k]

If you play an honour, then lead low next, you succeed if RHO has Ax or Kx or AKx.

[Antrax]

So is that the best play, assuming I mustn't lose three tricks?

[Fluffy]

the 9 works when LHO has Ax Kx AKx, and also when he has AK so I'd say low to 9 is better. Edited May 21, 2012 by Fluffy

[dburn]

If "missing AK10xx" means "missing AK1032", then you had better lead to the queen first. If the queen loses to the ace or king, lead low on the next round. If RHO plays high in front of the queen, play low on this round and high on the next.

 

The way to think about these things at the table is to consider cases where one line wins and the other loses. We compare "queen then low" with "finesse the nine" and we see that the former:

 

Wins when RHO has AKx, Ax, Kx (six of the possible 3-2 breaks);

Loses when RHO has A10x, K10x, 10x (six of the possible 3-2 breaks);

Breaks even when RHO has AK10, AK, A10, K10, Axx, Kxx, 10xx, xx (eight of the possible 3-2 breaks).

 

We are on the verge of tossing a coin when we realise that "queen then low" also wins when LHO has the singleton ten. Since this is the only 4-1 break that we can handle (once RHO has failed to play the ten on the first round), we conclude (correctly) that "queen then low" is better than "finesse the nine".

 

Similar calculations for combinations missing the nine, missing the eight etc. are left as an exercise for the reader.

[Antrax]

Lead what low? I have a singleton opposite QJ98765

[Stephen Tu]

When he says "queen then low", he means lead the singleton toward the Q. The second round, lead a low card, i.e. not the jack.

[Antrax]

Ah, thanks. Is there a fast approximation for this, at the table?

[gwnn]

Ah, thanks. Is there a fast approximation for this, at the table?

Not that I know of, but sometimes it is just clear that an option is much better than others. Luckily, the harder it is to count them, the closer the alternatives are and the less it matters. However, it pays to look at some of these combinations in suitplay. That way you will develop a sense of which plays you're supposed to compare in the first place!

[Phil]

Something that should get some mention in this thread is when you hold T9x as defender to falsecard with the T/9. It shouldn't matter when declarer has x / QJ8xxxx (although a tired declarer might choose to try to pin your T9 instead of drop your KT). It will matter when your partner has AQ however.