The Squeeze-Trim-Endplay: Hand
From actual play, reported by Nigel Guthrie:
You opened 1D, your partner bid 1S, you bid 2NT, and your partner raised you to 3NT. The opening lead was the K, with Righty showing out. You of course lead the 10. Righty takes the A and leads a small heart.
You have a diamond threat and a club threat. So you have squeeze possibilities if Lefty has the long diamond. There are also endplay possibilities if Lefty has the queen of diamonds.
But by far the best possibility is a squeeze-trim-endplay. The club suit is perfect -- the lead of the 10 will endplay Lefty, and if Lefty pitches two clubs, a club can be set up by leading the suit. Lefty has two winners in clubs, which means you need two winners in the exit suit. Actually, you have two winners in every suit. The loser count is 3, which you have.
You have to guess which suit Lefty is most likely not to have an exit card. On this hand, that is spades. After you cash your spades, you have
Lefty cannot deceive you in clubs -- you have a count on that suit. So Lefty has to save 3 clubs. If Lefty has two hearts and two diamonds, you cannot go wrong. If Lefty has saved 3 of a red suit, you should be able to guess which one.
On this hand, Lefty shows out on the second round of spades, then pitches a club, heart, and diamond. If Lefty has three hearts left, then he started with 1-5-2-5 distribution and at least 10 HCP. That isn't likely. If Lefty has 3 diamonds left, he started with 1-3-4-5, which is more plausible.
So you cash your hearts, Lefty pitching diamond on the second round. You have
Now you know that Lefty has 2 diamonds and 3 clubs left. You trim the diamonds and lead your club honor.
You could have run the squeeze-trim-endplay in a more conventional fashion if you had ducked the opening club lead. Then Lefty would have had just one club winner remaining. That would have been better if you did not have a double stopper in the two possible exit suits. But you still would have been faced with the same choices -- which suit is Lefty least likely to have stopped (spades), then which suit is Lefty least likely to have saved. There also would have been marginal chances if you guessed wrong. For example, if you found out on the third round of spades that Lefty had an exit card in spades, you could have squeezed Lefty in the red suits while you still had a spade winner.
Squeeze-Trim-Endplay Variations (two losers in the endplay suit)