I was North on this online deal. I don't do it often, but I was playing as a favor with one of my frequent cruisers:

KJ54 A432 A52 A2

86 KQJ865 Q 8754

South opened 2 and I raised to 4. Everyone passed and the K was led. How should it be played? It looks easy, but since it was matchpoint scoring, overtricks could be important.

Declarer won the A and embarked on drawing trump. They turned out to be 3-0 and this was the Real Deal:

Vul:None Dlr: South	KJ54 A432 A52 A2
73 1097 K86 KQJ93		AQ1092 -- J109743 106
	86 KQJ865 Q 8754

One round of trump was survivable, but not more than that. My partner drew three rounds and could no longer make the contract. With both spades wrong, declarer had to lose 2 spades and eventually 2 clubs.

Even though I've taught it a million times, my students continually make the same mistake. If you have losing cards to trump in the short hand, then don't draw trump. Here, declarer should give up a club and trump clubs in dummy. At some point one round of trump is okay, but after ruffing both clubs in dummy, the spade play (which nothing good comes of here) is for an overtrick. Down one was a horrible score, but not a bottom. Why not?

At some tables, I suspect East bid 4 over 4. I would have. Now when North doubles, East might run to 5, also doubled. Imagine North's surprise when that contract makes for 550 East-West!