Source: ACBL 2007 Bulletins You can read Part I, II and…Clicking Here
South plays in 3NT after opening 1
and rebidding 1NT. Some players would choose to rebid 2, wishing to emphasize the diamond suit but the hand is balanced with honors, in all of the unbid suits, so 1NT is best because it is so descriptive.
As an aside, when South bids 1NT he shows a hand with 12 to 14 high card points and balanced distribution. North knows pretty much what South has. If South rebids 2, however, North will expect six diamonds. As you can see, South does does not have them. Further, North cannot tell if South has 12 HCP or 16 HCP because South 2 bid is very non-descriptive. His shape can range from something similar to the example hand to a 1-2-7- 3 distribution. He might even have a void.
Back to the play. North raised to game and West leads the 
J. This looks like a good contract given that there are 11 potential tricks.
South wins the K and tries the diamond suit. There’s a bad diamond break, however, with West having four to the jack. Does this mean that 3NT is down?
It means that the contract is not as good as it was before because South will only get three diamond tricks. He could try to set up a long diamond, but that could be fatal if the defenders get around to cashing their club tricks. Good defenders, by the way, will notice that South has the A and Q and likely the A K as well. This will account for 13 high-card points.
If South gives up a diamond, the defense should know to switch to clubs even if neither defender has signaled for a club switch. Some plays are obvious if you look at the evidence.
So having played the three top diamonds you are committed to getting four spade tricks. If spades divide 3-3 you have nine winners. Do they?
Here is the complete deal:
When South plays on spades, he will find that East has four of them. They are not very strong, but East’s holding will stop South from cashing four tricks in the suit.
Does this mean that 3NT was fated to go down? If you are a spot watcher, you will see the answer. Hopefully, you saw the answer in time.
If you are not a spot watcher, read on. Note the spade suit. Look at all four hands. South is the recipient of a small miracle. On this deal, spades divide 4-2, but it doesn’t matter because West was dealt the doubleton 
J 10. If South plays A K, the J-10 drops and South’s 9 is good.
South can cash the 9 and go to dummy to win the last spade trick. Nine in all. There is one little catch, however. On this layout, like many others, the issue has to bee noted in time to cater to it. South has to win the heart lead and play on spades immediately.
When he sees the spade honors come down, he can come to the 9 and return to dummy with the K. Only if South saves the K as an entry will this contract come home. It costs nothing to play this way. If everything behaves, there are 11 tricks, and in the event that spades are as they are, South will get at least nine of them. Plan ahead.