Fourth Suit Forcing
When three suits have been bid by our side in an auction where the opponents are not bidding (e.g. you open 1♦, next hand passes, partner responds 1♥, next hand passes, and then you bid 2♣, passed to partner), responder usually has enough information to decide the final contract. But, when they do require more information, and when there are enough points for at least game, they need a bid which keeps the auction going, but asks partner for a further description of their hand.
Answer: bid the fourth suit! 1♦ p 1♥ p 2♣ p 2♠ - it’s called Fourth Suit Forcing, and is an artificial tool which allows us to take the bidding more slowly when we have a game-going hand, and saves us from leaping to a contract, and guessing the best spot (usually the wrong spot!). Fourth suit forcing is designed to make responder’s bidding easier, when
The responder doesn’t know which game to play
The responder is strong and wants to make a slam try
The responder wants to go to slam but uses fourth suit first to set the trump suit.
Some play fourth suit as forcing for one round only, but it’s better used as game forcing. If you play it as a one-round force only, it’s hard to know which later bids are forcing and which are not. Playing it as game-forcing makes it simpler, and partner will not drop you below game under any circumstance! If fourth suit is forcing to game, then you need to find another non-forcing bid if you have a hand that’s less than a game force. Often this is 2NT to show 11, 12 points e.g. 1♦ p 1♥ p 2♣ p 2NT (= 11,12 points with a stopper in spades).
WHEN (to use fourth suit).
Fourth suit forcing would occur when the responder has bid a suit and the opener shows a second suit, typically:
1♠ 2♦ OR
2♣ 2♥ OR
It’s not likely here that we would play with the fourth suit as the trump suit. If the responder has values in the fourth suit, no trumps is often best. So, bidding the fourth suit is not promising length in that suit. The bid is artificial, and says: “game-forcing”. After that, there is no rush, because partner can never pass a bid lower than game! However, if the responder already knows which game to play, bidding the fourth suit is not necessary. To use fourth suit is to investigate more when we need to investigate!
HOW (to use fourth suit)
After hearing fourth suit, opener does not know what kind of hand their partner has. That will be revealed in the next round. So, opener should try to describe more about their own hand, eg support responder’s suit with three cards (there can’t be more than three, because with four-card support they would have raised in the first round), or bid no trumps with a stopper in the fourth suit or rebid one of their own suits with extra length.
The fourth suit bidder could easily have a hand where they want to play in no trumps, but perhaps has no stopper in the fourth suit:
The responder may have:
If opener bids no trumps over 2♦, fourth suit, in the above auction, they promise a diamond stopper, and suggest that it’s ok to play no trumps. If opener has no diamond stopper, we should probably try another game when the responder has these cards. But the reason for responder’s use of fourth suit forcing may also be that they are looking for something else, eg support for their own suit:
The responder may have:
The reason for bidding fourth suit here is to check out if partner has three hearts, in which case 4♥ on a 5-3 fit probably is better than 3NT as we may have only one diamond stopper. If the opener over 2♦ doesn’t show heart support, East can try 3NT.
The responder may also use fourth suit forcing and then rebid their own suit to show a six-card suit. If the responder bids1♥ or 1♠ and then later simply rebids the suit, the bid is not forcing:
2♣ 2♠ = not forcing, partner can pass
2♣ 2♥ (4th)
2NT 3♠ = natural, forcing to game. Usually a six-card suit.
(Thanks to GeO Tislevoll for this material, and his advice. We ran a very successful coaching session on this topic in August 2018).
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