This is based on a Real Deal from last year's ACBL International Matchpoint Game. As South, with both sides vulnerable, you hold:

64
KJ109873
Q8
A7
Perhaps this hand is too strong to preempt, or you don't like all the cards on the side, but I'm fine with opening 3. LHO doubles and partner raises to 4. Everyone passes and LHO leads the Q:

A10 A42 A954 8542

64 KJ109873 Q8 A7

It looks like you'll lose at most a trick in each side suit. In trumps, even if they are 3-0, you will play for the takeout doubler to have the void (starting hearts with the ace). Likely, you are playing for an overtrick. You can't do anything about the spade loser, but you should try to get rid of a club on the diamonds.

If you win the A to play a diamond to the queen, it loses to the king. West plays a spade to East's king and a club switch is won by your ace. Hearts are 2-1, but you have no overtrick.

Here is the real deal:

Vul:South Dlr: Both	A10 A42 A954 8542
QJ97 6 KJ73 KJ109		K8532 Q5 1062 Q63
	64 KJ109873 Q8 A7

After winning with the A, a diamond to the 8 is the winning play. Why would you do that? From West's takeout double and the lead (Q), you can place East with the K and almost all the remaining HCP with West. He must have both minor-suit kings. When the 8 loses to the jack, West plays a spade, but that is the last trick for the defense. Why? Later on, you will play your Q, which West must cover. Then, when you trump a diamond, the 10 falls, making the 9 good for a club discard. Lucky? A little, but worth trying. (Note: declarer should be careful on the heart to the ace to retain the 3, so he can later reach dummy for the good diamond).

Squeeze experts will note that the overtrick can also be made by ducking the first trick. West can eventually be squeezed in the minors.

If the title of this article were "Intra-finesse," that would have given away too much information.