[y66]

The textbook play when missing the queen and 3 other cards in a suit in which you are trying to take all the tricks is to play for the drop (the chance of dropping a singleton or doubleton queen is 53% according to Hugh Kelsey and Michael Glauert in Bridge Odds For Practical Players).

Do the odds change in favor of finessing when LHO has shown an unbalanced hand, for example, by overcalling at the 2 level, opening a weak-2 or opening a 3-level preempt?

Say you play small from KJ8732 toward A96 in dummy. LHO plays the 4. Ace. 5.

You play dummy's 6. RHO plays the 10. Do you always play the king (absent any other obvious clues from the bidding or play)?

[Codo]

No, you often finesse.

If one opponent had shown a shortness in your suit (by a double) he may still hold Qx instead of x, but the chance of x increased enough to finesse.

If one opponent had shown a long suit or even a two suiter, he is obviously more likely to hold a shortage in your suit.

I don´t know, where the borderline is, but if he had shown 6 cards in a suit, finessing is surely right.

The theory behind this is according to the principle of free places.
If you know so far that LHO has 6 spades and 1 Heart and RHO 2 Spades and 1 Heart, LHO has 6 free spaces but RHO 10. So RhO is a 10:6 favourite to hold any special card outside of Spades.

[FrancesHinden]

Assuming you can't pick up 4-0 breaks at all (or that alternatively you can always pick up one 4-0 break in which case the odds on all the following lines increase by just under 5%)

Then, as you know, with no information about the outstanding cards, the odds say that

Cash the Ace then the King = 53%
Cash one top honour then finesse = 51%
Finesse on the first round of the suit = 45%

If you know something about the outstanding distribution of the cards, then Justin has it nearly right:

- If you only know one card difference (so a suit is breaking 5-4, or 6-5) then it is exactly equal whether to cash the AK or play one top honour and then finesse.

- If you know two or more cards difference, then it is right to finesse on the second round. By how much it is right depends on the length you know: at the extreme if you know 12 cards in one hand before playing on the suit and 10 in the other it is 100% to finesse on the second round but if it is only that trumps have broken 2-0 then it is 55% to 53%

- It only becomes right to finesse on the first round (e.g. with AKJ10xxxx opposite a singleton) once you either know a lot about the hand already (i.e. not many vacant places) or there is a 5+ difference you know about in suit lengths, such as a suit breaking 7-2

[pclayton]

Jlall, on Mar 25 2008, 06:00 AM, said:

Not sure how accurate this is but my general rule of thumb is if you know TWO more of RHOs cards you finesse, and if you know only 1 more of RHOs cards you go for the drop. So if you know a suit is 5-4 and nothing else I would still play for the drop, but if you know a suit is 5-3 and nothing else I would hook.

There was a Bridge World article on this many years ago. My recollection is it takes a 3 card difference to swing the odds to a finesse instead of a drop. It's easy enough to determine though.

A 2 card difference is very close though.

[pclayton]

Yep, you guys are right. Its about a 3% edge for the finesse with a 2 card difference assuming a weak 2.

[Mbodell]

The other thing that can make a difference, although I'm not sure how much or how to weigh it, is if one opponent has shown most of the points (the one you'd finesse into) as well as the length in a side suit. From the weekend online:

Scoring: IMP

1♠!-2♦-2♠-P
P-3♦-3♠
All Pass

! - 10-15, 5+ spades

---

♦A-2-3-6
♦K-8-4-♠J
♠A-2-3-4
♣3-2-A-5
♠9-5-7-♦5

Here I decided the person bidding diamonds twice and already showing up with 7 of their points in AK of ♦ was more likely to be stiff spade than Qx. I was right this time, but would everyone agree this was the percentage line? The field didn't (or else, possibly, messed up the heart throw in since the 3-2 heart split had the 3 hearts with the long diamond hand who was 1-3-7-2 so as long as 2 rounds of clubs were played you'd get a ruff sluff) as only 4 of the 13 pairs in spades took 10 tricks (2 took 8, 7 took 9).

[jdonn]

Mbodell, on Mar 25 2008, 04:14 PM, said:

The other thing that can make a difference, although I'm not sure how much or how to weigh it, is if one opponent has shown most of the points (the one you'd finesse into) as well as the length in a side suit.

I feel it is consistently better in that situation to trust the shape inference more than the strength inference. For one thing, Qx in the suit bid on their right probably makes their bids less desirable than x anyway. Here it looks like diamonds were 7-3 (probably not 6-4 since no raise) so I really would be confident in finessing.