Posted 2006-March-09, 04:54
Let's suppose clubs are 4-1. RHO could easily have switched to a club from a 4-card suit looking at dummy, so we don't know which way clubs break.
We need to worry about who has the SK, who has the HA, who has the 4 clubs. That gives an awful lot of cases. RHO's holding is given below:
i) HA, 4 clubs, SKx
ii) HA, 4 clubs, SKxx
iii) HA, 4 clubs, Sxx
iv) HA, 4 clubs, Sxxx
v) -viii) as above without the HA
9-12) as above with HA, with singleton club
13-16) as above without HA, with singleton club
Ignoring the overtrick, or the second undertrick, taking the spade finesse works in cases
1,2, 5,6,7,8,9,10,13,14
Playing ace and another works in cases
2,4,6,8,9,10,11,13,15
Unless I've miscounted (quite likely), the spade finesse is better by one case.
Except that if you think RHO has 6 diamonds from the auction and opening lead, then cases 9-16 are more likely than 1-8.
So even ignoring the probability of getting forced off, it's not at all obvious whether it's right to take the spade finesse to avoid a club ruff.
Now factor in the possibility that RHO is 4-6 in the pointy suits (when you have to finesse) and it must be extremely close.
Oh, and you might like to think about what RHO needed for a 2D overcall in HCP, and what, if anything, you can read into the fact that he didn't force you at trick 2. Or that if RHO has Kxx xx AJ10xxx xx a heart return (ducked) at trick two would have given you the same problem (on that hand you finesse, I leave it as an exercise to construct hands where Ace and another would be better).