Like Astro, Aspro is initiated by a 2-level overcall in a minor suit when the overcaller or intervenor holds an unbalanced hand with at least nine cards in two suits (i.e. 5 in one and 4 in the other), at least one of which is a major.
- 2♣ shows hearts and another suit, and
- 2♦ shows spades and a minor suit.
The foregoing includes the possibility that the 2♣ overcaller holds both majors. Using Aspro with five spades and four or five hearts, the 2♣ bid is followed by 2♠ over partner's 2♦ or 2♥; with four spades and five hearts, one rebids 2♥ over partner's 2♦.
- The name is borrowed from a popular British brand of aspirin.
- Manley, Brent, Editor; Horton, Mark, Co-Editor; Greenberg-Yarbro, Tracey, Co-Editor; Rigal, Barry, Co-Editor (2011). The Official Encyclopedia of Bridge (7th ed.). Horn Lake, MS: American Contract Bridge League. p. 267. ISBN 978-0-939460-99-1.
- Crowhurst, Eric (1980). Acol in Competition. London: Pelham Books. p. 290. ISBN 0-7207-1273-4.
- In the description of competitive bidding, players are referred to as either the Opener (the first to make a bid, the Intervenor (the opponent who makes his side’s first bid), the Responder (partner of the Opener) or the Advancer (partner of the Intervenor).