Minor-Suit Fits: Hunting for 3NT First
With a minor-suit fit and game values, look for 3NT by checking the unbid suits are stopped, and head to five of a minor only when one is not.
When you find a fit in a minor, five of the minor needs eleven tricks, but 3NT needs only nine. So the first question is whether 3NT is possible. The answer usually depends on stoppers in the unbid suits.
Why it works
3NT fails when the defence can run a suit that neither of you can stop. If every suit is covered, nine tricks are normally easier than eleven. If one suit is wide open, the minor-suit game protects you because your trumps stop that suit after one or two rounds.
A worked example: One heart stopper decides it
Opener: ♠ A Q 4 ♥ 8 5 ♦ A K J 7 3 ♣ K 9 2 (17 HCP)
Responder: ♠ K 7 ♥ 9 6 3 ♦ Q 10 8 6 ♣ A Q 7 3 (11 HCP)
The Auction: 1♦ – 3♦ (a limit raise) – 3♠ – 4♦ – 5♦.
Opener's 3♠ shows a spade stopper and asks about the other suits. Responder has clubs covered but no heart stopper, so bids 4♦. Opener knows hearts are unguarded and bids 5♦.
3NT would fail on a heart lead: the defence hold eight hearts. In 5♦ declarer loses two hearts and makes eleven tricks with three spades, three clubs and five diamonds.
Change responder's hand to ♠ K 7 ♥ K 6 3 ♦ Q 10 8 6 ♣ Q 7 3 2 (10 HCP). Now responder bids 3NT over 3♠, and nine tricks are much easier than eleven.
Four common mistakes
Jumping straight to five of a minor without checking for 3NT.
Bidding 3NT with an unbid suit that neither hand stops.
Treating a stopper-showing bid as a new suit to play in.
Passing below game after a stopper-showing bid when the partnership has game values.
When the rule does not apply
With an extreme shape — such as a void and a long minor — five of a minor can be safer even with every suit stopped, because there may be few entries in no-trump. A single stopper such as K-x-x may not hold if the defence attack it twice. Partnerships also differ in how they show stoppers, so agree your methods.
Key takeaways
With a minor fit, look for 3NT first.
Show stoppers to check every unbid suit is covered.
If one suit is wide open, choose five of the minor.
Nine tricks are usually easier than eleven.