Suction

Suction is a (restricted) defense against 1NT that does not promise an anchor suit. Each suited overcall shows the next-higher suit OR the other two suits. The suits "wrap" so that 2 may show clubs, for example.

Double and 2NT are used to show non-touching two-suiters.

Bid	Meaning
Double	Clubs + hearts
2	Diamonds OR hearts + spades
2	Hearts OR spades + clubs
2	Spades OR clubs + diamonds
2	Clubs OR diamonds + hearts
2NT	Diamonds + spades

Overcaller should have a good 5+ card suit at the 2-level, or a 6+ card suit if forcing the bidding to the 3-level. Similarly, overcaller should have at least 5-5 length with any two-suiter that requires partner to bid at the 3-level.

In response to Suction, advancer usually assumes a one-suited hand, and bids that suit. If overcaller has only shown a two-suiter (i.e. Double or 2NT), then advancer usually takes a preference in either suit. Any other bid by advancer is natural.

The benefits of Suction:

1. Suction provides a way for all one-suiters and two-suiters to be shown.

2. Suction can cause headaches for the opponents. What does a double mean? A cue-bid?

The problems with Suction:

1. Unlike other defenses to 1NT, certain hands can't be shown at the 2-level, e.g. a club one-suiter or a minor two-suiter.

2. In the ACBL Convention Charts, Suction is disallowed in Basic and Basic+ ACBL events. It is, however, allowed in Open and Open+ events.