10 for sure
This deal comes from the 2019 U.S. Team Trials. With no one vulnerable, South held:
♠A K 6 5 3 ♥J 2 ♦AJ 8 2 ♣K 10 2
He opened 1♠. These days, we routinely open such 12-counts. Partner responded 2♣, game forcing. Now what?
There are three possible calls, none of them right or wrong: 2♠, 2NT or 3♣. I prefer that 2♠ guarantees at least six, so for me it is either 2NT or 3♣. Each is flawed – no heart stopper for the 2NT bid and only three clubs for 3♣ call. Because of the ♥J, I think I’d select 2NT. Regardless of your choice, partner jumps to 4♠ and you play there with the ♦K lead:
You win, I hope, and start trumps with the ace and king. It turns out West started with a low singleton. Ugh. Now what?
You have one discard on the fourth diamond, but still have to negotiate either the clubs or hearts.
If you continue with the diamonds, West turns out to have started with K–x.
With 10 cards in clubs and hearts, West is a strong favorite to hold the ♣Q. You can discard a heart on the fourth diamond and take a club finesse against West. How does that work? Let’s look at what I think should be the Real Deal (honestly, I never found out the real East–West cards):
A bit unlucky, down one. However, I wouldn’t blame it on luck. Once you discover that East doesn’t have all five missing diamonds, there is a sure thing. Declarer should finish running the diamonds, throwing a heart, then exit in spades. East takes his spade winners, but then has to play a heart or a club. Either way, declarer has 10 sure tricks. Try it!