This deal was (mis)played in a "world class" invitational online tournament last year. The declarer who fell from grace shall remain nameless. In a Team match (IMPs), South held:

 K10  
 AK96  
 Q75  
 KQ102. 

With both sides vulnerable, he was in 4th seat. Possibly with the good spots and honors in the long suits, this hand is worth more than a 15-17 notrump.  In fact, most hand-evaluation programs say it is worth about 18.  

Anyway, being creatures of habit, most of the experts in this event opened 1NT. Let's say partner invites (though you will see from the dummy that it is quite marginal) and you accept.

A65  QJ  108643  J75

K10  AK96  Q75  KQ102

Against 3NT, the 4 (standard is led). This is an excellent contract. You have 6 top tricks in the majors and can set up 3 more in clubs. In fact, this contract is 100%--there is no lead or lie of the cards that can set you.

Declarer played low from dummy and East played the J. Should you win or hold up? Since you might lose 3 diamonds (maybe West has something like AJx) and the A, you should win the first trick. What next?

You can unblock the QJ and then play clubs. This was the full deal:

Vul:N-S Dlr: West	A65  QJ  108643  J75
Q98432  87  A9  943		J7  105432  KJ2  A86
	K10  AK96  Q75  KQ102

Maybe you have spotted that I've led you down a careless path.

As is often the case, trick 1 was crucial. The K was a key entry to declarer's hand. Surprisingly, a top-level player made the mistake of playing low from dummy at trick 1. Maybe this was greed, hoping the lead was from the QJ and that an overtrick might result (though there still could be entry issues).

Once declarer played low from dummy, 3NT can be defeated. When declarer wins the K and plays clubs, East must hold up the A until the third round. Now, declarer can't take 9 tricks (the hearts are blocked). Unblocking the hearts first and then playing clubs also fails (the defense wins the 3rd round of clubs).

The solution is basic. Win trick one in the proper hand. Save the K. Win the A from dummy, cash the hearts and then play clubs. Nine easy tricks.

I thought this deal was too simple for my "Intermediate" bridge column, but if a top expert screwed it up...