I got an email from a friend and multiple national champion. "I screwed up this deal in the Vanderbilt. You can use it in your column, as long as I stay anonymous."

See if you can do better. He (South) held:

 KJ83
 8
 QJ102
 AJ73

With both sides vulnerable, as South, he opened 1, and West overcalled 2NT to show a two-suiter in hearts and clubs. Expert partnerships have agreements here. North cuebid 3 to say that he had spades (five or more) and at least invitational values (3 would have shown a weaker hand). RHO competed to 4 and South tried 4. LHO went on to 5 after which North's 5 bought the contract.

109654  KQ  AK973  5

KJ83  8  QJ102  AJ73

 How would you play on the K lead? Aside from the two aces, the Q is a problem. With West having all the hearts and clubs, it makes sense to finesse against East in spades. Accordingly, declarer won the A and ruffed a club to dummy (he didn't want to touch diamonds, risking a ruff there). He led the 10, intending to finesse and a look at the Real Deal will show you what happened.

Vul:Both Dlr: South	109654  KQ  AK973  5
7  AJ764  4  KQ10984		AQ2  109532  865  62
	KJ83  8  QJ102  AJ73

 Good news--the Q was onside. Bad news--East rose with the A and played a heart to West's ace. West won and played another club. East overruffed the dummy for down one.

What was the error? Crossing in diamonds would have worked, but that was risky. The correct play is a heart at trick two. This cuts the communications. When East later wins his A, he has no way to reach his partner for the overruff.  Declarer can reach dummy in diamonds to take the winning spade finesse.