Source: www.bridgeforeveryone.com
This deal gets my vote for the best defense ever. It occurred during the 1985 International Team Trial to pick the U.S. team for that year’s Bermuda Bowl world championship. Try it for yourself first.
Dlr.: South Vul: Both
Your partner leads a low spade. South ruffs your jack, cashes his ace of clubs, and ruffs a club with dummy’s eight of diamonds (partner plays the eight and ten of clubs). How would you plan the defense?
The full deal is ….
⇓
⇓
⇓
⇓
⇓
⇓
⇓
⇓
⇓
⇓
⇓
⇓
⇓
⇓
⇓
⇓
⇓
⇓
(a) Limit raise or better with three or more spades
(b) At least 5=6 in the minors
Eddie Wold (West), judging that declarer would want to ruff clubs in the dummy, led a trump. This defense can be best, but it wasn’t here. As we will see in a moment, a forcing defense was better.
The declarer, Lew Stansby, could have got out for down one by winning in hand, cashing the ace of clubs, ruffing a club with dummy’s jack of diamonds, and drawing two more rounds of trumps. He would have lost two club tricks to West and a heart trick. But declarer won the first trick with dum-my’s jack of diamonds, so suffered two overruffs in clubs by Mark Lair (East). Stansby also had to lose a club trick, so East-West were plus 500.
Bobby Wolff (West) led a spade.
Marty Bergen (South) ruffed East’s jack, cashed the ace of clubs, and ruffed a club with dummy’s eight of diamonds. East, Bob Hamman, paused to assess the deal. What did he do? Judging from West’s eight and ten of dubs that declarer was 5=7 in the minors, Hamman could see that South was in trouble. His clubs couldn’t be that strong, because he hadn’t drawn trumps. And how would declarer get back to his hand for more club ruffs? Not with trumps, because he needed those in the dummy for the club ruffs. And if he ruffed a spade, South would lose trump control. So, Hamman, refusing the opportunity to overruff with the nine of diamonds, discarded.
Declarer exited from the dummy with a heart, but Hamman won with the king and forced Bergen with another spade. A club ruffed with the jack of diamonds was followed by a heart ruff in hand, leaving this position: 
Declarer ruffed a club with the five of diamonds, but now Hamman overruffed and tapped again with a spade. Declarer finished with his five trump tricks, two ruffs in the dummy and the ace of clubs: down 800. That was a seven-imp gain in a match won 339-334 by Hamman’s team.
Hamman was understandably awarded the Defense of the Year prize by the International Bridge Press Association, and his team won the Bermuda Bowl that October. Why was this so good? Because almost every other player would have overruffed the eight of diamonds, then decided what to do — too late.