Hands are from Adventures in Bridge, October 11, 2018.
South: ♠K102 ♥K95 ♦A1052 ♣1063
North: ♠J9874 ♥A7 ♦J7 ♣AQJ2
West (to the right of North) opens 1NT (15-17). By Mel's rules, North should bid. You have three spade losers (by Losing Trick Count); one heart loser; two diamond losers and one club loser for a total of 7 losers. The sum of two longest suits (spades and clubs) is 9. Subtracting 7 from 9 leaves 2—enough to compete. So bid 2♠ (for spades and a minor—Cappelletti/Hamilton) or two clubs (for clubs and a higher suit—DONT)—whatever your defense to 1NT is. North-South can make 4♠.
Proper defense—always a challenge—will set 1NT three tricks for +150 N/S. 2♠ making four is +170 for N/S.
To make 4♠, North must be careful NOT to squander the ♣10. Leading low in clubs from the South hand TWICE picks up the doubleton King, while leaving the ♣10 to handle the 4-2 break.
North: ♠AQ103 ♥A4 ♦KJ1065 ♣A9
South: ♠K5 ♥62 ♦A9873 ♣K532
I passed in the South seat, as did West, and partner opened 1♦. I fell from grace by bidding 1NT. Usually it is correct to “grab” the no trump when you have two Kings to protect in your hand. However, in this case, partner raised me to 3NT which makes five. (Our defenders did not fall for a pseudo squeeze, so we were held to 11 tricks.)
If I say 2♦ (inverted, even by a passed hand), partner might get excited with her five diamonds and control-rich hand. She can bid 2♥, and I can then bid 2NT which should pretty much guarantee possession of both black Kings (possibly QJx in one of the black suits instead).
Partner can bid 4♣ (Gerber over a 2NT bid) and I will show one Ace. Then, 6♦ looks like a likely shot from the North hand. If I have the ♦A and both black Kings, the only worry is the ♦Q—even so I might have five diamonds, or the Queen could easily fall.
Out of 7 pairs, only Ron and Mary Huffaker bid the diamond slam. Most pairs were playing 3NT, with most defenders fell from grace, allowing South to make seven once (played in the North with a spade lead into the ♠AQ10x), and six twice. It is worth looking at the E/W hands and the logic for E/W defense.
West leads the ♥Q. If Declarer takes the ♥A and reels off five diamond tricks, East can see from Dummy that he has sole responsibility for the fourth round of spades (Rule of Parity). East's first discard confirms his attitude signal at trick one that he loves hearts. Then East can discard ONE spade—partner should know then that you have five of them because you would not discard from a four card holding looking at that Dummy.
However, East must look more deeply into the hand. Once partner's doubleton the ♦Q falls, you know Declarer will be taking five diamonds, three spades (she must have the ♠K for her NT bid) plus one heart. That means both defenders will have to come down to four cards. Since you have to guard spades, you cannot keep hearts and also worry about clubs. You should give up on clubs IMMEDIATELY, to send a message to partner that he has sole responsibility for guarding clubs. [If Declarer has the ♣K AND the ♣J, you are doomed anyway.] You should keep ONE good heart because if you give up entirely on hearts, partner will not be able to keep four clubs and one heart in the end game and will be squeezed.
West can discard two spades and one heart. You know you are not setting this contract, so don't hang onto all your hearts! You are the only one who can guard the fourth round of clubs, and Declarer can easily have four clubs on this auction.
Now Declarer reels off three top spades. East has no difficulty in following suit. West can afford to discard three more hearts, trusting partner does have the winner in that suit, and keep all four clubs. Declarer will lose two clubs in the end game.
If Declarer ducks the first heart to tighten up the position for a potential squeeze, the defenders can simply give each other count in hearts, and both end up discarding all their hearts. Then, East guards spades and West guards clubs, and 11 tricks is the limit for Declarer.