This deal comes from the 2012 San Francisco NABC (Open Board-a-Match Teams). South held this beautiful hand, but faced strong preemption:

A7
A3
AK5
A107543
. 

The opponents, at favorable vulnerability (what else?), start with 3 on your left, raised to 5 on your right. There isn't much to do but double (you'll deal with the consequences later, if need be). Partner surprises you not by bidding spades, but by jumping in spades! He bids 6! What's that all about? It's hard to imagine he doesn't have great spades (and probably something on the side), so you boldly raise to 7.  LHO doubles.

Oops. This means he either has a trump trick (not likely, since he would probably just pass and take his down one--without potentially chasing you to a making 7NT), or he is making a Lightner double to try to get an unusual lead. Looking at all your clubs, it sure smells as if he has a club void.  So, you run to 7NT (you didn't think you'd be the dummy in one of my columns, did you?) and everyone passes.

KJ106542 5 J92 K9

A7 A3 AK5 A107543

West leads the Q and you count your tricks. Outside of spades you have only 5 sure winners. Even if spades run for 7 more tricks, you will be a trick short. The Q might fall, but a better chance is that one player holds the Q along with club length. On the run of the spades, he won't be able to protect both minor suits.

The $64,000 question is: How will you play the spades? From LHO's double of 7, he is likely void in clubs. That points towards him having possible spade length (even though he did preempt). What about RHO? For his raise to 5, is he likely to have Qx or Qxx? Probably not. To test your theory about LHO's club shortness, let's say you win the A and play a club. As expected, West shows out.

You go up with the K and come to the A (all following low). You might as well cash the AK next (in case you learn something more about the distribution). Nothing interesting happens-only low cards show up.

Next comes another spade and LHO plays low. The moment of truth is here. If you get this wrong, you are likely down 7 tricks or so (but a loss on a board is just like a bottom at matchpoints--it doesn't matter by how much).

All indications from the above dialogue point towards the finesse. Furthermore, to make the contract, you need RHO to guard diamonds (along with clubs). If he has only one spade, that increases the chances that he was dealt more diamonds, hopefully with the queen.

Vul: N-S Dlr: West	KJ106542 5 J92 K9
Q83 QJ109742 1043 --		9 K86 Q876 QJ862
	A7 A3 AK5 A107543

Your finesse wins! You run the spades and RHO does hold the Q. He has to abandon that card or let go of his club guard--so you emerge with all 13 tricks and a spectacular +2220 for a win on the board. (The other table played in 7X East-West down 6.)