When playing a weak No Trump system, a player will open One Club and rebid One No Trump with 15 to 17 balanced, and a player will open One Diamond and rebid One No Trump with 13 to 14 balanced.
The bidding: South, with a balanced ten to 12 HCP’s, opens One No Trump and partner passes because he knows game is out of reach. West stays quiet with his hand because he knows the opponents are in the wrong spot.
If West shows his diamond suit using Cappelletti, he first bids Two Clubs. North will pass and East will bid the Two Diamond relay which West will pass. North will then balance with a double and North and South will find their Heart contract.
East and West, however, stay quiet and South ends up in the wrong contract. North needs 13 points to use Stayman so they miss their four-four major fit.
The Play: West leads the King of Diamonds, and East wins the Ace and plays the Diamond Five. West rattles off six Diamonds and East discards the Spade Eight showing he wants a Spade led once West runs out of Diamonds.
East and West will get six Diamonds and three Spades for down three and +150.
In Diamonds, East and West can only get +110 because North leads the Club Queen and when West tries to ruff a heart, trump will be led twice.
However, North and South will never let a Diamond contract be played. They will play a Heart partial making three. West will lead his stiff Club and South will win the King with his Ace. He will cash two rounds of trump and run clubs. West will ruff but should not do so.
West must refrain from ruffing a club and when he gets in with either a Spade or a Diamond, he should play his last trump to reduce the amount declarer can cross-ruff.
West’s best lead is a trump. However, if he leads his singleton and ruffs a club, declarer will win two Hearts, four Heart ruffs and three Clubs making +140. If West leads trump three times and refrains from ruffing, declarer will win three Hearts, two Heart ruffs and three Clubs making +110.
Cappelletti was mentioned as a good bidding defense against a weak No Trump, but this example shows that passing is also a good defense.
