An ACOL 4NT opening bid shows an extremely strong hand, usually a one-suiter, that only needs to hear about which aces (if any) partner holds in able to bid a slam. The responses to the ACOL 4NT are:

5 0 aces
5 Ace of diamonds only
5 Ace of hearts only
5 Ace of spades only
5NT Any two aces
6 Ace of clubs only


Opener's rebids are natural. His hand must be good enough, of course, to play at the five-level opposite an aceless, trickless hand.

See also

  • ACOL 2C
    A strong, conventional opening bid showing a balanced 23 HCP or an unbalanced, game-forcing hand.

  • ACOL Two Bid
    A strong ACOL 2, 2, or 2 opening bid.

  • Strong 2C Opening Bid
    The Standard American method of using 2C as a strong, artificial opening bid.

  • Strong Two Bid
    The Standard American method of using 2, 2, or 2 opening bids to show strong hands.

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