During the Covid period where everyone was playing online, I received numerous cases to review. Accusations of "self-kbbitzing" or being on the phone with one's partner were rampant. One player was recorded for this action: Holding

A2
A6
653
AJ9632,
he opened 1. Partner responded 1 and he rebid 2. Partner now bid 2. What would you do? I think 3 or 3 are the main possibilities. This player jumped to 3NT. He caught partner with a suitable dummy with diamonds stopped. 3NT is a terrible bid, but you can't convict a player based on only one such action. Maybe he was just an inexperienced player, or made a bad bid. Anyway, this was the Real Deal:

	A2 A6 653 AJ9632
1083 J97 A10874 85		Q964 Q432 Q9 Q107
	KJ75 K1085 KJ2 K4

The teacher in me saw an opportunity. The start of 1-1-2 is fine. But South's 2 makes no sense. There is no 4-4 spade fit (North would have rebid 1 with 4), so South has an easy 3NT call at his second turn.

West would lead the 7 (4th best) and East would play the Q.

Now what? If South takes the K and works on clubs, East gets in and plays another diamond, down one.

This is a safe-hand/danger-hand lesson. Declarer has to realize that East is the danger hand. If South wins trick one and then East gets in and plays another diamond (and they are as shown), he is down. So, he should holdup on the first diamond. If they turn out to be 4-3, no problem.

Once East wins the first trick, there is no winning defense. Declarer will eventually work on clubs and easily make his contract. (If after the Q wins and diamonds get cleared, declarer later plays the K and takes a finesse to the J, not caring if it loses).

What about winning the first trick and playing A, K and another club? That will work if East started with any doubleton club (or singleton 10), but why rely on this when the indicated line works on most normal layouts.

After the actual jump to 3NT by North, East led a spade and declarer had no problems.