A Defensive Hand from the Software DEFENSE
By Mike Lawrence

West must give South a sluff and a ruff by leading another diamond. It does not matter where South takes the ruff. Most likely, he will ruff in dummy and discard his spade. No spade losers for South. Another club is taken by West who leads another diamond. South ruffs this one, but still has two club losers.

The key is this.

West counted South's winners. West saw that South has two spade tricks, five hearts tricks, and a ruff in dummy. Leading diamonds ensures that South has only eight tricks.

Leading clubs can never win. Even if East has the king of clubs, it does not gain a net trick for the defense. By leading diamonds, West gets all the available tricks wherever the king of clubs is.

In this case, the key was for West to count South's winners. He has just eight so West defended in a way that could not possibly give South a ninth.

Nice try by South. Against some defenders, this line would have worked.