West leads the ♠3 (fourth best). You play low from dummy, East wins the ♠Q and returns the ♠8, West following with the ♠2. You continue with the ♦A K, but West shows out on the second diamond discarding a low heart. Now what?
You have plenty of chances after the diamonds turn out to be 4–1. Play the ♣A Q and a low club to dummy. If clubs are 3–3, your troubles are over as you have nine tricks. If West turns up with four clubs, your best bet is the heart finesse. If somehow you sensed West had the ♥K, you could make the contract by returning to your hand with the ♦Q forcing yet another discard from West. Assuming West clutches onto his K–x of hearts, West will discard a spade. Now you can exit a spade allowing West to cash three black suit winners, but you get the last two tricks with the ♥A Q.
If East turns up with four clubs, cross back to the ♦Q and exit the ♠J. Assuming an honest lead, West can cash three spades, but after the fun and games are over, West will have to lead a heart, allowing you to score tricks eight and nine with the ♥A Q.
The opening lead is the ♥7 (fourth best). Trumps are 2–1 and East is the one with the singleton. Plan the play.
Many experts play that a response of 4NT to a four-level, minor-suit overcall is natural. Had North–South agreed to this treatment, and had
North bid 4NT instead of 5♦, I would not have a quiz hand as there are 10 top notrump tricks. North,
however, raised to 5♦, and now you are in a contract that needs 11 tricks.
In order to make this contract, you must avoid the loss of two club tricks, as you are destined to lose at least one spade trick.
Given that West has the ♣K in order to justify a first-seat, vulnerable opening bid (without the ♣K, and excluding the possibility that West has the ♠K Q J, West can have at most 10 HCP), your best shot is to ruff the opening lead, cash the ♦A J and lead a low club. If the stars are in complete alignment, West will play the jack! Now you have 11 sure tricks: seven diamonds, at least two clubs, and two major-suit aces. But this is matchpoints so you must think “overtrick.”
Win the ♣A, ruff another heart and lead another low club towards dummy’s 10–5–4. If West plays the king (he may have to if he started
with king–jack doubleton), you have three club tricks which means an overtrick. Also, if the ♣10 holds, discard the ♣Q on the ♥A and ruff a club. If clubs go 3–3, score up an overtrick as both of dummy’s spades go away, one on a long club and one on the ♥A.
Okay, back to the real world where the stars are seldom in alignment. Say the 10 loses to the jack and a spade comes back. Win the ace and lead another low club. If the king appears, you have 11 tricks: seven diamonds, two clubs and two major-suit aces. If the ♣K does not appear, win the ace, discard the ♣Q on the ♥A and ruff a club. If clubs are 3–3, you survive, as dummy’s long club is your 11th trick.
Given that West started with the ♣K, this line loses if East started with a singleton ♣J (highly unlikely), or a doubleton ♣J.