Test Your Play

Assuming West has five diamonds and East three, the idea is to try to develop four club tricks without letting West get the lead. The technically correct play is to cross to the
♥A and lead a low club catering to the singleton queen in the East hand. If East plays the queen, play low and if West follows, you have
at least nine tricks: four clubs, two spades, two hearts and the span style=”color:#ff0000;”>♦A.
If East follows with a low club, win the ace and cross to the king (ducking the second club in dummy if West plays the lowest outstanding club). Unless West has four clubs, East will have to win the trick and again you have four club tricks or nine in all. If West shows out on the second club, rise with the king and lead a third club toward the jack, ensuring nine tricks. If West follows to the second club with the highest remaining club spot, rise with the king, and if both follow, lead a third club hoping East has the queen, better than playing on spades. If West plays the ♣10 on the second lead of clubs from an original holding of Q–10–9–x, win the ♣K and take the spade finesse.
Another play with intriguing possibilities is to run the ♠J at trick four if not covered! Yes, a Chinese finesse! If the spade finesse loses, and a heart comes back, win the ace in
dummy and play clubs as described earlier for four tricks. Your “fake finesse” wins outright when West has a spade holding of Q–x–x and doesn’t cover. In theory it loses when West started with ♣Q 10 9 x and East has ♠Q x x. But given the way you plan to play clubs, (ducking the 9 on the second round of the suit), you will go down anyway with that layout.
Notice on the actual layout of the black suits, East must cover the ♠J. Also, whenever you start with a low club from North, East must play the ♣10! If East plays the ♣8,
you can win the ace and lead a low club. When West plays the ♣9, your percentage shot is to play low hoping East has 10–x. (Q–x is okay, too.) If East started with the 10–8 doubleton,
your avoidance play has worked and you have nine tricks, minimum.

This one logs in at 100% against any distribution of the East-West cards.
Win the ♦K (nice play), draw trumps and lead a diamond (key play). Say West wins and leads a club to the queen and king. Now what? The most you can lose is a heart as one heart goes off on a club. Say West shifts to a heart instead of a club and whichever heart you play loses to the next higher heart. No matter. What can East do? The best East can do is exit a diamond which you ruff. Now you can lead a second heart, setting up the suit for a club discard.
If you don’t exit a diamond after drawing trumps and take a club finesse instead, East wins and leads a low diamond to West. Now a heart return sinks you outright if East has the ace–queen or forces you to guess the suit if he doesn’t.
If, instead of taking a club finesse, you start hearts after drawing trumps and misguess the suit (or maybe you can’t guess it right), East wins and puts West in with a diamond, and now
a club return to East’s king sinks your ship. You will lose two hearts a club and a diamond.
Notice East’s play of the ♦Q at trick one, the only diamond he can play to have a chance of defeating the contract. East must arrange to keep a
diamond entry to the West hand in case you lead a club or a heart before leading your remaining diamond. But you would never do that, would you?