[Winstonm]

Here is the critical suit that needs to be played for 4 tricks in a NT contract.

K4 opposite AJ983.

RHO opened 1H in third seat. LHO led a diamond indicating that RHO holds diamond length as well. Taking the position that LHO holds spade length, what is the best play?

This hand occurred in a team match and I led the Jack from hand - this turned out not so wonderful as RHO held Qx and LHO 10xxx. Clear cut error or bad luck?

[temp3600]

Let's call cashing KA line 1 and running the J line 2.

Anything works if the suit is 3-3.

If the suit is 4-2, then line 1 succeeds in 9/15 cases (at least one honor with East). Line 2 succeeds in 6+1/15 cases (QTxx with West or QT with East) plus half of 8/15 cases (East holds Tx) = 11/15

If the suit is 5-1, then we need to find East with a stiff honor. Line 1 always succeeds (1/3), line 2 only succeeds when East has the stiff T (1/6).

Nothing works if the suit is 6-0.


So... line 1 is probably slightly better than line 2.

It's interesting to note that running the 9 is inferior to running the J. It has the same odds when the suit is 4-2, but cannot win when it is 5-1, whereas the J wins when East has a stiff T.

[whereagles]

I once saw Helgemo running the jack on one such case. It made, and smothered the singleton 10!

How did he guess? I don't have a clue. Opps were silent throughout... lol.