West led the ♦A, then the ♦K which was ruffed by Declarer.  With one Ace already lost, and the ♠A to be lost later, Declarer could not afford to lose a trump trick.  Given the 5-0 break, avoiding a trump loser might seem impossible, but watch what happened!  After ruffing the Diamond at Trick 2, Declarer lost to the ♠A, won the Spade return, and ran the ♥T.  The good news was that this held the trick and, when West showed out, that (surprisingly) wasn’t really bad news at all!

 

Next, a Spade was ruffed, and three Clubs were cashed, ending in Dummy.  Here was the end position (West was merely a spectator at this point):

 

            Dummy      ♠ 64

                                ♥ A

                                ♦ T  

                                                 East   ♥ Q743

            Declarer     ♥ KJ9

                                ♣ 6

 

Dummy led a Diamond and East now had to suffer the ignominy of (a) being forced to ruff that in front of Declarer; then (b) under-ruffing when Dummy ruffed a Club; and finally (c) at Trick 12, falling victim to a Trump Coup, being obliged to ruff with his Q7 in front of Declarer’s KJ!  It really was most unsporting of Declarer to play the hand so well.