1 - Cue-bid
2 - RKC Blackwood
3 - Two Key-Cards along with a void

West leads the ♦K against your slam (the opponents lead king from ace-king to ask for count), East playing the nine, and switches to a trump at trick two. Plan the play.

Solution:
There is some flexibility in the order you time your plays. Say you win the spade switch in dummy and ruff a diamond in hand. You ruff a club in dummy, and ruff a diamond in hand, East discards a heart. So you cannot establish diamonds anymore; maybe clubs may work out better, so you ruff another club in dummy. You ruff another diamond to come back to hand, East discards another heart.

Both opponents follow to your ♠A. When you cash the ♣A, West follows with the ten, but when you cash the ♣K, West discards a diamond, meaning clubs don't come through either. No problem, the contract can still be made on a double squeeze. You continue by cashing the ♣K, West discarding a heart. This is the position before you play your last trump:

	♠ -
	♥ A8
	♦ Q
	♣ -
♠ -		♠
♥ Q10		♥ K9
♦ K		♦ -
♣ -		♣ Q
	♠ J
	♥ J
	♦ -
	♣ J

West needs to keep the ♦K, so he has to discard a heart. The ♦Q has served its purpose, and can be discarded now. It is East's turn to feel the pinch; he has to keep his ♣Q, so he pitches a heart as well. You play a heart to dummy's ace, and win the last trick with the ♥8.

As long as West has the ace and king of diamonds, and East has length in clubs, the double squeeze operates. It should be noted that it is not necessary to try to establish diamonds by ruffing them out, as you can bank on the double squeeze.

Analysis:
Bridge Baron's double dummy solver points out that an initial trump lead will defeat the contract, as you will not be able to ruff two clubs in dummy without squandering the ♥A entry for the double squeeze. A heart switch breaks up the double squeeze, but that is of course a double dummy play. In fact, even a heart switch does not defeat the contract, as declarer can establish hearts as this is the only suit to divide favorably.

Bridge Baron's Line of Play
Bridge Baron got this one right. Winning the spade switch in dummy at trick two, Bridge Baron ruffed a diamond in hand and ruffed a diamond in dummy. Demonstrating that it did not need the diamond suit to be 4-3, Bridge Baron ruffed the ♦Q in hand, to ruff a second club in dummy. The rest of Bridge Baron's play was along the lines of the recommended line, and Bridge Baron eventually executed the double squeeze to make the hand.
Par Contract Analysis:
The par contract on this deal is 5♠ by North-South.

Bridge Baron deal No : N4927-89533-07272-29526-81633-97800