West leads 
J. Plan your play.
THE TRICK AT TRICK ONE From a Swiss Pairs Event:
West led the J and South took the A. A diamond to the king was followed by the 
3: six – queen – ace. West switched to the 
J, won in dummy, and the 4 was won by East’s king. East cashed the K only to discover that South still had the clubs stopped.
To cash the Q would give South the ninth trick with the 9 and so East reverted to hearts. Dummy won and when the 9 lost to the 10, the 8 had become the extra trick South needed.
As the play went, East could have defeated the contract by rising with the K on the first round of spades. The K and Q are cashed and then a spade gives West two more tricks to take 3NT one down.
Declarer was lucky to have East err and to find the spades blocked. As happens so often declarer’s mistake came at trick one. If South lets the J hold, he can set up an extra trick in spades without giving the defenders the chance to collect two club tricks.