In Bridge unless you have a vision and work hard at it to succeed in getting the desired results, you will be just an average player with limited ambitions. Those who wish to excel at Bridge also make a relentless pursuit of locating the key cards at Bridge. This they achieve by keeping their concentration level up to the mark. Such players make good defenders and fine dummy players. Let us illustrate by example. Suppose you are east holding the following cards in a contract of 4H bid by south after passing initially and bidding 1H on partner's opening of 1C, finally closing at 4H on partner's strong relied of 2NT with west leading the 4D to the following dummy spread on your right as east.
The declarer inserted the 10D taken by your JD which holds. As east plan your defence. The first thing that should strike you immediately is that looking at the 19HCP dummy with declarer holding at least 7-8HCP+, there is very little left with your partner. Giving declarer his 6 carder trumps (most likely headed by Q) make the trumps solid. The missing black queens are also most likely to be with the declarer to give him his necessary 6 to 7 HCP points. As east you can clearly see that both your black kings are on, which along with 2 diamonds can still sink the contract of 4H by south. But there is more to it than meets the eye. Complacency can cost dearly. Can you put on your thinking cap and plan an impregnable defense that can easily net in the required 4 tricks that appear for the taking.
Let us see what happened at the table where the actual hand was played. When east, certain in his mind that the black kings are winners, cashed his AD followed by the third diamond for declarer to ruff, the heavens fell for him as south after knocking out the trumps which broke even 2-2 gave east his club trick, but managed to discard a spade from his hand on the 4th club and so made his contract as he held:
Although all three finesse in diamonds spades and clubs were wrong for south, he still sailed home because of a defensive lapse on east's part. Can you guess now what should east have done? Yes-a little bit of far-sighted vision would have sent a clear signal to east that if declarer held 6 hearts, 2 diamonds, with his remaining 5 black guards split 3-2 the declarer was always going to have 4 tricks from the black suits by 3 sure club winners and the ace of spades. These 4 tricks combined with 6 solid trump tricks added up to the required 10 tricks to make 4H. The defenders need to reason out the possible holding and line of play that declarer would adopt. East fell from grace when he cashed his AD at trick 2, instead of playing a low diamond to his partner's promised honour which surely could be nothing else than KD. This was mandatory on the part of east to shine with good defense, for the simple reason that the play of the hand hinged on share timing. Before declarer could get his timing right by knocking out east's club king east should have given his partner the chance to lead though dummy's spades and thus make his KS a winner. At the table east didn't take the time to visualize that if declarer held 3 diamonds instead of 2, the third diamond was going nowhere to escape, but as in the actual case a spade loser could escape easily, as it did. The return of 9D would have sent the declarer packing after west, taking KD, attacks spades immediately. Defense is no doubt the most difficult aspect of Bridge. But cashing in at the opportune moments provided, good and alert defenders strike gold for they think far ahead for the move after next.

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North Dummy    East
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     A 5    4 8 3 2
 A K J 3        9 8
  Q 10 2      A J 9
A J 10 9    K 7 6 5
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         Q J
Q J 10 7 6 4
         7 5
       Q 8 4
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