Over the past few decades, bidding philosophy has changed. Methods have evolved and improved, and expert partnerships reach good contracts more often — if given a free run in the auction.

So an emphasis on obstructing the opponents’ auction has taken hold. There is no denying that preempts work. Still, your preempt may impel your opponents to bid with all the more vigor, push them into an unlikely contract — and help them make it.

In today’s deal, North lacked the values to act over West’s preempt. But when South backed in with four diamonds, North lifted to six. West led the king of clubs, and South took the ace.

With no clues from the auction, South might have cashed the K-A of diamonds, then finessed in spades to try for a club discard. But after West’s preempt, South’s approach was different — and successful. He led a trump to the king and trump to his jack, playing West for a singleton (especially since West might have led a major-suit singleton if he’d held one). After taking the ace of trumps, South led the nine of spades and let it ride.

East took the ten but was end-played. No matter which major suit he returned, South would get a free finesse and his 12th trick.

Anyone would have preempted as West; I expect I would have myself. But if West passes, North-South may not reach slam. After all, they have only 29 high-card points and not much shape. I would bet that most pairs would stop at 3NT. And if they did reach six diamonds, South would not have a roadmap to guide his play.

West dealer

N-S vulnerable

NORTH

S A K J 7

H K J 5

D K 9 3

C 7 6 4

WEST

S 5 4

H 10 8 3

D 4

C K Q 10 9 8 5 3

EAST

S Q 10 8 6 3

H Q 9 7 2

D Q 8 6

C 2

SOUTH

S 9 2

H A 6 4

D A J 10 7 5 2

C A J

West North East South

4 C Pass Pass 4 D

Pass 6 D All Pass

Opening lead — C K

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