Fourth-suit Forcing

Fourth-suit forcing is the popular term for the idea that a bid by responder of the only unbid suit at his second turn is an artificial force. Most play that it is forcing to game, although some play it is forcing one round only. The bid is made when responder has doubts about strain or level. Suppose you hold:

♠ K 2
A K J 4 2
Q 10 3 
♣ 8 5 3

You are South and this is the bidding:

North South
1 1
1♠ ?

You have enough values for game, yet no bid is suitable. You cannot bid 3NT with three low clubs. Many players agree that a jump to 3 shows a six-card suit and is invitational. If you have that agreement, you cannot rebid 3. In other words, you don’t have a convenient rebid.

Playing fourth-suit forcing, you should bid 2♣, a conventional waiting bid.

Partner’s first obligation is to raise hearts with three-card support. His second obligation is to bid 2NT. You don’t promise clubs to bid 2♣ — it is an artificial bid. Your partner needs a club stopper, therefore, to bid notrump. Partner can rebid his second suit to show extra length. In the sample auction, for example, 2♠ would show six or more diamonds and at least five spades. If partner has neither heart support nor a club stopper, he should rebid his first suit — 2 in the previous auction.

Practice Hands

Here are some examples to clarify how fourth-suit forcing works.

What do you call holding:

♠ K 10 7
A K 8 7 4
J 10 4 
♣ A 2

North South
1 1
2♣ ?
ANSWER
This one is easy — bid 2♠. You want to see if your partner has three-card heart support. If not, then you will bid 3NT.
 

What do you call holding:

♠ K 10 7 2
A K 7 4
J 10 4 
♣ A 2

North South
1♣ 1
1♠ ?
ANSWER
Bid 4♠. Do not bid 2, fourth-suit forcing. You have four-card spade support and values for game — bid it.
 

What do you call holding:

♠ K 10 7 2
A K 8 7
J 10 4 
♣ A 2

North South
1 1
2♣ ?
ANSWER
Bid 3NT. Partner does not have four of either major. You have values for game and stoppers in the unbid suit. You don’t need to bid fourth-suit forcing. It is used when you aren’t sure where to play the contract.

Other matters to discuss

  1. Fourth-suit forcing is not used if one partner is previously a passed hand. (Other agreements are possible.)
  2. Fourth-suit forcing is not used after a 2/1 response. It is used only when the one player bids one of a suit and the partner responds at the one level
  3. Fourth-suit forcing is not used when opponents intervene in the bidding. You can use the cuebid instead as a forcing probe.
  4. A jump in the fourth suit shows a 5–5 hand and is strongly invitational.
    Consider this auction:

    North South
    1 1
    1♠ 3♣

    You might hold:
    ♠ 5 2
    K Q J 4 3
    5
    ♣ A J 10 4 3

  5. One auction merits special discussion:
    North South
    1♣ 1
    1 ?

    In this auction, most players treat 1♠ as natural and forcing. A jump to 2♠ denies a four-card spade suit, but promises values for game.

  6. Fourth-suit forcing is not used after a reverse or after a 2 opener. In these cases, you are in a forcing auction, so the artificial bid is not needed.

To read the full series in PDF format, click here.

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