Bidding : 4S (N) - Pass (E) - Pass (S) - Pass (W)

Opening Lead : 5 of Clubs (W) = top of a doubleton

Declarer (N) counts 3 possible losers : 2 losers in Clubs, plus perhaps one in Spades if the trumps break 4-0.

Declarer Play
Establishing a long suit
West wins the first trick with the Club King, then plays the Ace, and at trick 3 a small Club, ruffed by East with the Jack, too high for Dummy to over ruff. A Heart lead is won by Dummy, and all remaining cards in Declarer's hand are now winners, 10 tricks in total.

Note that East West have a 4H contract cold in their hands and even have a small chance of making 5H on any lead other than Diamonds.

Score = 4 x 30 trick pts + 300 bonus pts = 420 pts total

Bidding : 4D (E) - 5D (W)

Opening Lead King of Spades (S) = top of a solid sequence

Declarer (E) counts 3 possible losers : the three small Hearts in his hand.

Declarer Play
Ruffing losers with Dummy's trumps before drawing trumps
The opening leads is won by Dummy's Ace, who then leads a small Heart. North wins with the King and, guessing what Declarer is up to, leads a trump at trick 3.
Declarer wins the trick with the Ace and at trick 4 leads a small Heart, ruffed in Dummy. Dummy leads back a Spade, ruffed by Declarer. At trick 6 Declarer leads his last small Heart ruffed once again by Dummy.

At trick 7 Dummy leads his last Diamond to take out the only remaining trump from the opposition. The remaining tricks are won by A and K of Clubs and Declarer's trumps, making 12 tricks in total.

The Defence could have held Declarer's tricks to 11 by leading a trump as opening lead. West, after winning the Heart Ace at trick 2 would have lead a second trump. This would have reduced Dummy's trumps to one only with which he could ruff Declarer's Heart losers.

Score = 6 x 20 trick pts + 300 bonus pts = 420 pts total

Bidding
3H   (S) - (4D   W) - 4H   (N) - (5D   E) -
Pass (S) - (Pass W) - 5H   (N) - (DBL E) -
Pass (S) - (Pass W) - Pass (N)

South 's 4D preempt shows 7 tricks. North, who can count 3 quick tricks (AS plus 2 tricks for his Diamond void), therefore bids confidently to 4H. When the Opponents raise their bid to 5D, North believes they will easily make that contract. He therefore makes the sacrifice bid of 5H.

North realises that his side will probably go down 1 or 2 tricks but even when doubled this will only add up to 100 or 300 minus points. The Opponents' Diamond contract by comparison will cost -600 point.

Opening Lead : King of Clubs (W) = King from A K Q x

Declarer (S) counts 3 possible losers : The Aces of Clubs and Hearts, plus a small Spade loser. He may perhaps be able to get rid of the Spade loser in his hand by developing Dummy's long Club suit.

Declarer Play
Sacrifice bid   -   Developing a long suit by ruffing
West wins the opening lead and then leads his Queen of Clubs, ruffed by Declarer.
At trick 3 Declarer plays a small Diamond and ruffs it in Dummy. Dummy then leads a small Club ruffed by Declarer. Declarer (trick 5) leads his remaining small Diamond, once again ruffed in Dummy. Dummy leads a 4th round of Clubs (trick 6), ruffed by Declarer, while West drops his last remaining Club, the Ace !

Declarer now leads a small trump to Dummy's Jack, won by East's Ace. East, at trick 8, leads another trump, won in Dummy with the 10. All enemy trumps are now drawn. Dummy leads his Club 10 which is now a winner, on which Declarer discards his small Spade loser.
All remaining tricks (A K of Spades and the remaining trumps) are now winners.
N S have miraculously pulled a rabbit out of the hat. Instead of losing -600 points by the enemy's 5D contract, they have made their 5H doubled for a plus total of 650 points.

Score = 10 x 30 trick pts + 300 + 50 bonus pts = 650 pts total

Bidding
3S    (W) - (4H   N)   - 4S   (E) - (5H   S) -
Pass (W) - (Pass N)   - 5S   (E) - (Pass S) -
Pass (W) - (DBL N) - Pass (E) - (Pass S) -
Pass (W)

West 's 3H preempt (vulnerable) shows 7 tricks. East, who can count 3 quick tricks (KS, AD, plus 1 tricks for his Heart singleton), therefore bids confidently to 4S.

When the Opponents raise their bid to 5H, East believes they will probably make that contract. He therefore makes the sacrifice bid of 5S. He realises that his side will probably go down 1 or 2 tricks but even when doubled will only add up to 200 or 500 minus points. The Opponents' 5H contract by comparison will cost -650 point.

Opening Lead : King of Hearts (N) = King from A K x (x)

Declarer (W) counts 4 possible losers in his hand : 2 Hearts and 2 Clubs. He can ruff one of his Heart losers in Dummy, but the other 3 will probably remain.

Declarer Play
Sacrifice bid   -   Ruffing losers with Dummy's trumps
North wins the first trick, but seeing Dummy is now void in Hearts switches to the King of Diamonds forcing out Dummy's Ace which wins the trick. Dummy at trick 3 leads a small trump to Declarer's Ace which also draws the 2 enemy trumps. Declarer now leads his remaining small Heart, which is ruffed in Dummy.
Declarer can not avoid conceding two more tricks to the enemy in Clubs, making a total of 10 tricks. Only one down losing -200 points. This is an excellent sacrifice against a certain 5H contract by the enemy which would have cost - 650 points

Score = 1 Down vulnerable Doubled = -200 pts (+200 pts for NS)