# Trying to understand when to take a deep finesse?

This is from Dorothy Truscott Hayden's book "Winning Declarer Play".

``````                    Dummy
AQ9
West                                     East
?                                        ?
You
752
``````

She suggests first finessing the 9 and then the Q. Directly finessing the Q gives you 2 tricks only if West has the K. But doing the deep finesse gives 2 tricks when

• West has the King
• West does not have the King but has both the 10 & J

This is quite clear, but where do we stop on this? What if Dummy has AQ8 - do we still first finesse with the 8 in the hope that West 9,10,J?

``````    AQ8
JT9x    Kxx
xxx
``````

If you play small towards `AQ8` in dummy, `LHO` should play one of the `J`, `T`, or `9`. Then you can only score one trick in the suit. If the position is

``````    AQ9
JTxx    Kxx
xxx
``````

then splitting honors does not prevent you scoring the `9` (after `J`, `Q`, `K`, you can come to hand and repeat the finesse).

So the general answer is: only take a deep finesse if it can promote a trick.

• Your answer is very logical & I accepted it. But I find it very difficult to work such things out on the table. Is there a thumb rule that can be formulated for this - something similar to 8 ever, 9 never for the Queen finesse? – user93353 Nov 5 '17 at 13:31

To take off on Ruds' answer, if you have AQ9 in the dummy, you play the queen if West covers with the J or T, and the nine otherwise. This gains under the following circumstances.

1. The king is "onside" (with West), so playing the Q wins the finesse.
2a. The king is "offside (with East), but both J and T are onside with West. Playing the Q on say, the T uses up two opposing cards (T and K) for the price of one. You end with A9 in dummy against Jx (or more x's) in West.
2b. The king is "offside (with East), both J and T are onside with West, but West "ducks" with a low card. Then playing the 9 forces out the K from East, promoting your Q.

If you have AQ8 and West has JT9, he should play one of those. Then 2b no longer works because West will have JT against your A8. On the other hand, if E has K9 (or better), your 8 will lose to the 9, not drive out the K, so 2a no longer applies. Of course, 1 still applies.

Since you can't gain from playing 8 from AQ8, you play the Q straightaway and hope for the best.