Score ten points 4

As South you are declarer in 7NT.

N/NS		♠	K 9 7 6 5
		♥	Q J 3
		♦	A 2
		♣	Q J 3
		♠	A Q
		♥	A K
		♦	K Q 10 8 6 5
		♣	A K 2

West leads the ♣10, you win in hand with the ♣A.

Make your choice by clicking A, B or C and find out whether your line of play is the correct one. EW do not make any mistakes.

A I cash the ♠AQ. Then I cross to the ♦A and play the ♠K.
B I cross to the ♦A and play the ♦2 to the ♦K.
C I cross to the ♦A and play the ♦2 to the ♦10.

N/NS		♠	K 9 7 6 5
		♥	Q J 3
		♦	A 2
		♣	Q J 3
		♠	A Q
		♥	A K
		♦	K Q 10 8 6 5
		♣	A K 2

On the ♠K East discards the ♥4. So West had four spades including the ♠J.

A I play the ♦2 to the ♦K.
B I cash the ♥AK and the ♣K, cross to the ♣Q and cash dummy's ♥Q.
C I play the ♦2 to the ♦10.

N/NS		♠	K 9 7 6 5
		♥	Q J 3
		♦	A 2
		♣	Q J 3
		♠	A Q
		♥	A K
		♦	K Q 10 8 6 5
		♣	A K 2

West shows out on the ♦K. You now cash the ♠AQ and the ♥AK, cross to the ♣Q and cash the ♠K. Alas: East shows out. You are one down. Bad luck, admittedly: the diamonds 4-1, the spades not 3-3. But the way you played, you would not have made your grand slam either if both four card suits had been in one hand (a squeeze would have been possible then).
1 point for your troubles.

Click here for the entire lay-out.

N/NS		♠	K 9 7 6 5
		♥	Q J 3
		♦	A 2
		♣	Q J 3
		♠	A Q
		♥	A K
		♦	K Q 10 8 6 5
		♣	A K 2

West shows out and you are one down. Bad luck, admittedly: the spades not 3-3 and the diamonds 4-1. But the way you played, you would not have made your grand slam either if both four card suits had been in one hand (a squeeze would have been possible then). 1 point for your troubles.

Click here for the entire lay-out.

N/NS		♠	K 9 7 6 5
		♥	Q J 3
		♦	A 2
		♣	Q J 3
		♠	A Q
		♥	A K
		♦	K Q 10 8 6 5
		♣	A K 2

On the ♥AK EW both follow suit, as well as on the ♣K. But when you cross to dummy's ♣Q East sheds a small heart. On the ♥Q EW both again follow suit.

A I play the ♦2 to the ♦K.
B I play the ♦2 to the ♦10.

N/NS		♠	K 9 7 6 5
		♥	Q J 3
		♦	A 2
		♣	Q J 3
		♠	A Q
		♥	A K
		♦	K Q 10 8 6 5
		♣	A K 2

The ♦10 wins, West showing out. You have successfully finessed East's ♦J - which turned out to be necessary since he held four diamonds - and in doing so you made your 7NT contract. Yet your partner will have his doubts about your future dummy play, since in diamonds you took, without a valid reason, an in itself inferior chance. After all, the finesse was only necessary if the suit was not 3-2. But the suit will be 3-2 in 68% of all cases - without further information about the distribution that is. The chance your finesse would have failed was 50%, so your line of play would have cost more often than won. On the other hand: never criticise those who 'sniff out' the winning play... Therefore: 3 points.

Click here for the entire lay-out.

N/NS		♠	K 9 7 6 5
		♥	Q J 3
		♦	A 2
		♣	Q J 3
		♠	A Q
		♥	A K
		♦	K Q 10 8 6 5
		♣	A K 2

The diamond finesse was not your best chance at the moment you took it. Has the fact that East had two spades only, against West's four, influenced your decision? There is something to be said for this: since in West's hand two more cards were known than in East's hand, the chance of East holding a specific card (♦J) was now slightly over 50%. Only 'slightly' though: not enough by far to give up a 68% chance (diamonds 3-2) in order to take a chance slightly over 50% (♦J in East). But you know what they say: never argue with success. West shows out and you make your contract: 5 points.

Click here for the entire lay-out.

N/NS		♠	K 9 7 6 5
		♥	Q J 3
		♦	A 2
		♣	Q J 3
		♠	A Q
		♥	A K
		♦	K Q 10 8 6 5
		♣	A K 2

West shows out and East's ♦J wins the last trick. What went wrong? You played very well by postponing the decision in diamonds for as long as possible. In the end you had a complete count on the EW-hands. Did you miscalculate? 7 points for the correct planning of the play, despite the error on the moment suprème.

Click here for the entire lay-out.

N/NS		♠	K 9 7 6 5
		♥	Q J 3
		♦	A 2
		♣	Q J 3
		♠	A Q
		♥	A K
		♦	K Q 10 8 6 5
		♣	A K 2

West shows out, so your ♦10 wins the trick. You win the last two tricks with the ♦KQ. You played very well. You have postponed the decision in diamonds for as long as possible in order to find out as much as possible about the distribution in the EW-hands. The 4-2 distribution in spades became clear very quickly (had the suit been 3-3, you could have claimed). After three rounds of clubs and three rounds of hearts it became clear East had a doubleton in clubs as well (his doubleton in spades was already known). Twice he discarded a heart. On the ♥AKQ EW both followed suit. East's hand was an open book now: doubletons in both black suits and precisely five hearts. Ergo, East had four diamonds, so the finesse over the ♦J was 'marked'. 10 points.

Click here for the entire lay-out.

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

West leads the ♣10. South wins in hand with the ♣A and assesses his chances.

Top tricks
South counts twelve top tricks: the ♠AKQ, the ♥AKQ, the ♦AKQ and the ♣AKQ. His thirteenth trick is there if spades are 3-3 or diamonds 3-2, but also if the ♦J is bare or if East holds all five diamonds (which becomes clear on cashing the ♦A).

Which suit first?
When there are two long suits it is best - assuming there is enough communication between the hands - to first tackle the suit in which only one line of play is possible (in order words: postpone tackling suits in which there is a decision to be taken). Spades first therefore, in that suit is no choice; declarer can only cash the ♠AQ and then the ♠K (in order to see whether the suit is 3-3). In diamonds South has two possible lines of play: topping the ♦AK or topping the ♦A only, followed by a finesse with the ♦10. First South tries to get as much information as possible about the distribution in the EW-hands.

Out for the count
After winning the lead with the ♣A, South cashes the ♠A and the ♠Q, then he crosses to the ♦A in dummy. If the ♦J had come down or if West had shown out on the ♦A, the problems would have been solved. But neither happened, so declarer tables the ♠K. Had EW both followed suit, South would have claimed.

But alas (or perhaps fortunately, anyone can collect 13 top tricks...) East shows out, he sheds a heart. South now unblocks the ♥AK (EW following suit), cashes the ♣K (EW following suit) and crosses to dummy's ♣Q. In this trick East discards another heart. On the ♥Q EW follow suit once more.

South now has a complete picture of the distribution: East has turned up with doubletons in both black suits and had five hearts precisely (West followed suit three times; so did East and he discarded two hearts as well). South knows therefore East began with 2-5-4-2. Since West's singleton diamonds has dropped under the ♦A, South now takes the 'marked' finesse over East.

Tip: If the declarer has to take a decision in a suit, he should gather as much information as is possible about the distribution and points in the opponents' hands, before taking that decision. Meaning he takes his decision in the end game.

P.S. There is one more reason for the advised line of play. Suppose the lay-out above is altered, giving one of the opponents four (or more) spades and four diamonds with the ♦J. Let us say West but the squeeze (for that is what will follow) also works if it is East. After the ♣A, the ♠AQ, the ♦A, the ♠K, the ♥AK, the ♣K and the ♣Q four cards are left:

N/NS		♠	9 7
		♥	Q
		♦	2
		♣	-
♠	J			♠	unimportant
♥	-			♥
♦	J 9 7			♦
♣	-			♣
		♠	-
		♥	-
		♦	K Q 10 8
		♣	-

Now the ♥Q is played from dummy, South discarding the ♦8. What should West do?

For the technicians amongst us: in order to be able to execute this squeeze South must still have an entry card for his diamonds after playing the 'squeeze card' (here the ♥Q). If he had played the ♦AK before, the squeeze would not have been possible.

Note that South does not have to know the distribution. The only thing he has to do is pay attention on whether the ♠9 has become good after he has cashed the ♥Q. If so he cashes that ♠9. If not so he tries the diamonds top down.