West leads the ♥J. East discards a diamond, and you win the queen. Plan the play.
Start with a low club. If West rises with the king, you have 12 top tricks. If East captures the jack and gets out with a diamond, then cash the ♦Q, ♣A, ♠A and ♣Q, discarding a spade. If clubs are 3–3, you have the rest. If West has four or more clubs, cash your spade and diamond winners, squeezing West in clubs and hearts.
If East, the more likely suspect, has the extra club length, cash your remaining diamond winners, discarding a club from the table, then the ♥K and ♥A, leaving dummy with a low club, a low heart and a low spade while you remain with the ♠K Q 9. Because the heart and club threats are known to be divided, your last three spades must be high.
If the ♣J holds, cash the ♠A and lead the ♠7. If East follows, stick in the 8 ensuring four spade tricks and the contract. If East shows out on the second spade, placing West with six hearts and five spades, duck the spade and squeeze West in the majors on the run of the diamonds and the ♣A. Finally, if East splits his spade honors, you can develop four spade tricks by force.
Thanks to Barry Paul, Great Neck NY, for this one.
Opening lead: ♠A. At trick two, West leads a spade to East’s king. Plan the play from here. Hearts are 2–1, West having the singleton.
It can’t hurt to ruff the second spade high. Cash the ♥K, the ♣A K, cross to the ♥A, ruff a club high, cross to a heart entry in dummy and take the diamond finesse.
Say the diamond finesse wins. You now are 100% to bring this baby home regardless of how the remaining diamonds break. Exit with a low diamond. If the suit was 3–2, the most you can lose is one diamond trick. Say they break 4–1, and East has the four. East wins the second diamond and either has to lead a diamond and give you a free finesse or give you a ruff-sluff, allowing you to ruff in dummy and discard a diamond, leaving you with the blank ace.
Say West is the one with the four diamonds, and he ducked with K–10–9–x, K–10–x–x or K–9–x–x. With K–10–9–x, he should have won and exited with a high diamond, ensuring a second diamond trick. If he doesn’t, he has to win your diamond exit and is endplayed and never does get his second diamond trick. Too tricky for his own good.
If West started with the other two holdings and ducks the ♦K, he can win the low diamond exit with the 9 or 10, but is endplayed and doesn’t get a trick with his remaining K–x.
If West wins the ♦K and exits a diamond from his remaining 9–x–x or 10–x–x, it can’t hurt to play the 8 from dummy. It will win the trick and you remain with the A–J.
The trap is not to cross to dummy’s last trump after your diamond finesse wins to repeat the finesse and try for an overtrick. It is a terrible disease playing IMPs called matchpoint-itis. If East shows out, West can no longer be endplayed, as he has two diamond tricks plus a safe spade exit, and you lose two diamond tricks and maybe a partner.