At the 1981 European Teams Championships Norwegian Leif-Erik Stabell, playing against Israel, lands his 6♣ contract in an ingenious way.

E/—		♠	7 4
		♥	Q 3 2
		♦	K Q 9 8 2
		♣	8 5 3
		♠	A K 6 2
		♥	A K
		♦	4
		♣	A K J 10 6 2

¹ 16⁺ HCP, conventional, forcing
² Fewer than 8 HCP
³ Relay
By means of relay bids South has gathered information about North's hand

West leads the ♠3, third or fifth best. East contributes the ♠J and Stabell wins with ♠A. He cashes the ♣A, dropping West's ♣Q.
Stabell has already decided and hands you his cards.
How would you continue?

Solution

Declarer can set up a diamond trick (or even two, if West has the ♦A) but after drawing trumps he cannot enter dummy in order to pitch (a) spade loser(s) on the good diamond(s).
It looks obvious therefore to cash the ♠K, the ♥A and the ♥K, then ruff a spade in dummy and pitch the other spade loser on the ♥Q.
However, Stabell had taken a good look at the ♠3 lead. Most probably West had either a three card suit or a five card suit. In the latter case East had a doubleton in spades and would overruff dummy, twice even. If so, declarer was in danger of never being able to enter dummy.
He saw a possibility to improve on his chances considerably if East had, in addition to the feared doubleton in spades, the ♦A as well. Therefore declarer cashed the ♠K, the ♥A and the ♥K. Next he played his singleton diamond to the ♦K (red cards have been played):

E/—		♠	7 4
		♥	Q 3 2
		♦	K Q 9 8 2
		♣	8 5 3
♠	Q 10 8 5 3			♠	J 9
♥	10 8 4			♥	J 9 7 6 5
♦	7 6 5 3			♦	A J 10
♣	Q			♣	9 7 4
		♠	A K 6 2
		♥	A K
		♦	4
		♣	A K J 10 6 2

East won with the ♦A (if he ducked, declarer would be home) but was now thrown in! If he played a red card, dummy would win and declarer could pitch his spade losers on the ♦Q and the ♥Q. So East returned the ♣7. Stabell let this ride to dummy's ♣8. Then he pitched his spade losers on the ♥Q and the ♦Q.
Note the importance of South cashing the ♠K first, before playing the diamond: by way of this Dentist's Coup he removed East's safe exit card.

At the other table the Israeli declarer was in 6♣ too. He also got a spade lead (but lacked information about West's spade suit). He cashed the ♣AK and the ♥AK and ruffed a spade in dummy. East overruffed: down one. 17 IMPs to Norway.