Here's a hand from a club evening. I was kibitzing since we were bye, and I saw a good player mess up the hand. Lets see if you can do better.
Opponents were silent, the good player (but usually not 100% concentrated on club evenings) sitting in South, playing with his wife. He likes to gamble a bit on club evenings, which explains the auction:
1♠ - pass - 2♥ - pass
2♠ - pass - 3♣ - pass
3♦! - pass - 6♣ - pass
6♥ - Dbl - 6NT - pass
pass - pass
(3♦ is natural, NOT 4th suit forcing)
After the 6♣ bid, North was thinking and sighing before bidding 6♥. Anyway, you're in 6NT and you get a small ♦ as lead. Plan the play.
Declarer made a few errors. He started with ♦J which held the trick. However, this blocks the hands completely. Next he played a ♥ from dummy to his King, knowing RHO has the Ace. This makes sure you can't even rectify the count for a squeeze. In the end he had to concede 2 tricks for -1.
If you give the hand a good look, you should be able to find a good line of play. You have 11 tricks if ♦Q is onside (good chance after this lead) and ♣s behave. This is your only chance anyway... So suppose all minor cards are nicely divided, you need one more trick. You have the perfect setting for a double squeeze, and you can rectify the count easily by conceiding ♥A. You'll have a ♦ menace against West and a ♥ menace against East, with ♠ working as your double menace. The biggest problem will be communication. That's why you shouldn't finesse ♦ at trick one, but just play low to your Ace. Now you're not in trouble whenever opponents play ♠. Next, as planned, we play ♥ to the Q, giving RHO a choice: either he takes and rectifies the count, or he ducks and you have your 12 tricks by playing a low ♥ back to your King (still only when the minors behave).
It's probably more easy to follow if you can see all the hands now:
1) Suppose RHO takes ♥A and returns a ♥:
You can't come back to your hand in the end, so the squeeze card should be in South. This means you should play ♦s first, followed by the ♣s, ending with
On the last ♣, LHO has to part with a ♠, you discard the small ♦ which has done his work, and RHO can't keep his high ♥ and 3 ♠s. A simultanous double squeeze gives you your 12th trick and a top score.
2) What if RHO takes ♥A and returns a ♠:
Now the cards lay a bit different. You can't go to dummy, except with ♦. This means you should play your ♣s before your ♦s! This will result in a non-simultanous double squeeze. West will be squeezed first, East will be next. The position where West has to surrender is quite early:
West still has ♠Jx, ♥J and ♦QTx. He can't part with a ♥ or a ♦, so he discards a ♠. Since LHO didn't discard his ♦, we throw one from the dummy. Now we still have to squeeze RHO in both Majors. Finesse the ♦J, and on the play of ♦K RHO is caught in a simple squeeze in the Majors.
RHO still has ♠Qx and ♥Tx and has to unguard one of the suits.
I was convinced there was always a double squeeze, but not everyone agreed. I checked with GIB and I was proved to be right. Now that you know how to play the hand after a ♦ lead, can you figure out what to lead with West's hand to defeat the contract?
Only a spade lead will kill the squeeze, because EW can ruin all communications required for the squeeze. If South tries to rectify the count by playing ♥Q, RHO should take his Ace and return ♥ immediately. Now declarer can't go from one hand to the other after the squeeze card, and this means there can't be any squeeze anymore.