Fourth Suit Forcing in Bridge Bidding
An artificial game-forcing bid when three suits have been bid naturally
Fourth Suit Forcing is a powerful bidding tool for experienced partnerships. When three suits have been bid naturally during the auction, bidding the fourth suit is artificial—it does not show that suit. Instead, it sends a clear message to partner: "I have game-forcing values but no clear bid. Tell me more about your hand."
This convention solves a common problem in constructive bidding. Sometimes responder has enough strength for game but cannot determine the best contract without more information from opener. Rather than guessing, Fourth Suit Forcing buys a round of bidding so opener can further describe their hand shape and stoppers.
When to Use Fourth Suit Forcing
Use Fourth Suit Forcing when all of the following apply:
- Three suits have already been bid naturally by your side
- You hold 12+ HCP (game-forcing values)
- You have no clear natural bid—no fit to raise, no suit to rebid, no stopper to bid notrump
- You need more information from partner to choose the right game contract
Requirements at a Glance
- Points: 12+ HCP by responder (game-forcing values)
- Auction: Three suits already bid naturally by your partnership
- Artificial: The fourth suit bid says nothing about your holding in that suit
- Agreement: Most pairs play this as game-forcing at the 2-level and above
The Bidding Sequence
Step 1: Three suits have been bid
Opener bids a suit, you respond in a new suit, and opener rebids a third suit. Three of the four suits are now accounted for in the auction.
Step 2: You bid the fourth suit (artificial and game-forcing)
This is artificial—it says nothing about your holding in that suit. It tells partner: "I have game-forcing values but need more information to place the contract."
Step 3: Opener describes their hand further
| Opener's Rebid | Meaning |
|---|---|
| 2NT / 3NT | Shows a stopper in the fourth suit; suggests notrump as the contract |
| Raise responder's suit | Shows 3-card support for responder's suit (belated raise) |
| Rebid own suit | Shows a 6+ card suit (extra length in their first suit) |
| Rebid second suit | Shows extra length in the second suit bid (e.g., 5-5 shape) |
Step 4: Place the contract
| Situation | Your Bid |
|---|---|
| Partner bid NT (stopper in fourth suit) | Raise to 3NT or explore slam |
| Partner raised your suit (3-card support) | Bid game in your major or explore slam |
| Partner rebid their suit (6+ cards) | Support partner's suit or bid 3NT |
Example Hand
Your Hand (Responder, South)
♥ K Q 10 8 4
♦ 9 5
♣ A J 6
HCP: 14 | Shape: 3-5-2-3 | Problem: Game-forcing values but no clear bid over 1♠
The Auction
| North (Opener) | South (You) | Explanation |
|---|---|---|
| 1♦ | Opens in their longest suit | |
| 1♥ | You respond in your 5-card major | |
| 1♠ | Opener shows a second suit—three suits now bid | |
| 2♣ | Fourth Suit Forcing—artificial, says nothing about clubs | |
| 2NT | Opener shows a club stopper | |
| 3NT | You place the contract in game—stoppers are covered |
Without Fourth Suit Forcing, South would have to guess between 2NT (underbid, not forcing, and no club stopper guarantee) and 3NT (overbid if partner has no club stopper). The convention lets the partnership exchange the information needed to bid accurately.
Common Mistakes
- Using Fourth Suit Forcing with a real suit: Remember, this bid is artificial. If you genuinely want to show the fourth suit, you need to bid it and then bid it again on the next round, or find another way to convey your message.
- Using it without game-forcing values: Fourth Suit Forcing commits your side to at least game. With only invitational strength (10–11 HCP), you should find a different bid such as a simple 2NT or a preference bid.
- Opener forgetting it is artificial: When partner bids the fourth suit, do not pass. It is forcing. Describe your hand further—show a stopper, raise partner's suit, or rebid your own suit.
- Confusing it with a natural bid: In some auctions at the 1-level (e.g., 1♣-1♦-1♥-1♠), the fourth suit may be natural rather than forcing, depending on partnership agreement. Discuss this with your partner.
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