Answers:
1.
West leads the
♠4. East plays the
♠J. Do you hold up? How do you play the diamond suit?
Hint: You can make your contract by playing diamonds. What can hurt you? Can you do anything about it?
Answer: Your winners are three hearts, one diamond, and two clubs. You also have one spade trick if you want it, or you can promote a spade trick later. You can promote two more tricks in diamonds, and can finesse in diamonds so that if West has the
♦K, you won't lose the lead. It is when East has the
♦K that your contract is in danger.
Only the spade suit can set you. If you win this first trick, West holds the
♠A and
♠10 left and if he started with five spades, East could win the
♦K and lead his only remaining spade through your finessable honor and West will run the suit to set you.
Once you see the problem, preventing it is easy. Don't win the first spade. With the
♠KQ holding intact, there's no way West can run enough spades since E-W can clear the spade suit but East won't have any spades left to lead upon winning the
♦K.
I specified IMPs, but I would play the same way at matchpoints.
2.
West leads the
♠4. East plays the
♠J. Do you hold up? How do you play the diamond suit?
Hint: You can make your contract by playing diamonds. What can hurt you? Can you do anything about it?
Answer: Again, your winners are three hearts, one diamond, and two clubs, and will get a spade trick. Again, you can promote two more diamonds, but tis time it is only West that can obtain the lead (if East has the
♦K, you will lead high honors from the dummy until East covers.)
If you hold up, East can lead his remaining spade, West can win the ace and lead a third spade, and he will have two good small spades, with the
♦K as his entry to cash them.
What happens if you win the first trick (say with the
♠K? You have the
♠Q5 left, and since West is the only one who can gain the lead in diamonds, your
♠Q is protected from attack. West can cash his ace and let your queen win, or West can lead low and your queen stops. Either way, you'll make an overtrick, and West is better off leading another suit to hold you to nine tricks (although that might not be his best play to try to set the contract.)
Why did I suggest winning with the
♠K instead of the
♠Q?
Again, I would play the same way at IMPs or matchpoints.
3.
West leads the
♠4. East plays the
♠J. Do you hold up? How do you play the diamond suit?
Hint: You can make your contract by playing diamonds. What can hurt you? Can you do anything about it? Can you increase your chances that the wrong defender doesn't gain the lead?
Answer: Again, your winners are three hearts, one diamond, and two clubs, and will get a spade trick. This time you can promote three more diamonds and can, if you wish, keep West out of the lead. However, the
♠4 lead tells you that the opponents' spades are split 5-4 (there's only one spade lower than the
♠4 in the opponents' hands, so West should have four or five spades.) If East has the
♦K, you can't stop him from leading a spade through your remaining honor if you win trick 1, and you can't prevent the run of spades if you hold up at trick 1. Or can you?
It's really too bad that the player that I could lose to isn't West. If West was the one who gained the lead in diamonds, I could win the first spade, protecting my spade holding. I don't mind if West wins the
♦K, but it's curtains if East wins it.
Since I don't mind if West wins the
♦K, perhaps I should ignore the finesse and play the
♦A! First, win the first trick. Lead the
♦Q to tempt West to cover, but when he doesn't, play the
♦A. On a good day, you drop the singleton
♦K and take eleven tricks. If the
♦K doesn't drop, keep leading diamonds and hope West wins the
♦K since your spades will be protected if West gains the lead. You will have given up the second overtrick that was available by taking a winning diamond finesse, but that's a small price to pay to make your contract when East's
♦K is singleton.
At matchpoints, I would not make this play; I would simply take the diamond finesse. Everyone will be playing in 3NT, and you can't afford to make ten tricks when everybody else is making eleven; you get the same matchpoint result as if you went down 1100. While you will go down on a contract that you could have made when East has a singleton
♦K, that singleton king doesn't happen enough to give up a trick that the other South players will get the half the time that West holds the
♦K.