Fourth Suit Forcing (4sf)

    Using 4sf, the bid of the fourth suit is forcing to game (variation: just one round).

Opener opens one of a suit.
Responder bids a different suit, without jumping.
Opener rebids yet another new suit, without jumping.
Responder rebids the final unmentioned suit, without jumping.

The 4sf bid itself says nothing about the suit itself, rather telling Opener to bid a third time.

Why Responder uses 4sf
Opener Responder
1 1
2 2*
  • Responder has a 5 card suit and is looking for 3 card support (possible 8 card fit):
    AK765 72 A43 QJ8
  • Responder has a fit for one of Opener's 2nd suit and plans to bid the suit next:
    AK54 7 A43 QJ765
  • Responder has a fit for Opener's FIRST suit, slam interest:
    AK54 7654 AK4 K2 and plans to bid the suit next.
  • Responder is looking for a stopper in the 4th suit to try 3N:
    AK54 72 6543 KQJ
  • Responder actually has the fourth suit and slam interest:
    AK765 72 AKQJ9 2
    • Opener's Bid after 4sf
    Opener Responder
    1 1
    2 2*
    ?
    Assuming 4sf to game, opener bids a third time as follow:
  • 2: 6 card suit *
  • 2: 3 card support
  • 2NT: stopper, fewer than 3 spades, more than a minimum
  • 3: 5+ card suit
  • 3: 3+ card suit
  • 3NT: stopper, fewer than 3 spades, minimum opener
    *Sometimes a 2 response, with only a 5 card suit, is necessary when other responses are less satisfactory.

    Responder Shows a Fit for Opener's Suit
    • Opener Responder
    1 1
    2 2*
    2NT 3/3?

       Often 4sf conceals a fit and establishs a low level game force.
    Responder's third bid in one of opener's two suits, below game,
    usually announces slam interest:
    Bid 3 with: AK54 7 A43 QJ875
    Bid 3 with: AK54 QT87 A2 AQ3

    Responder Shows a Longer First Suit
    Opener Responder
    1 1
    2 2*
    2NT 3


         If Responder's repeats her first suit after her 4sf bid,
    she announces 6+ cards in that suit (and slam interest):
    Bid 3 with: AKJT76 7 AJ3 AJ3

     

    Responder Shows Slam Interest after Opener Supports
    Opener Responder
    1 1
    2 2*
    2 3/4?

         If Opener announces 3 card support for responder's first suit:
    Responders with minimum forcing hands bid game straightaways:
  • Bid 4 with: KQT85 72 A43 KJ3

    • Responders with better hands bid otherwise:
  • Bid 2N with a balanced: AKQT5 72 AQT KT3
  • Bid 3 with: AKQT5 72 AKJT5 3
  • Bid 3 with : AKQT5 2 AJ43 KJ3

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