Bidding and conventions
Two over one game forcing
Two over one is a bidding system, widely played in North American tournament bridge, in which a new-suit response at the two level to a one-of-a-major opening is forcing to game. It also makes the 1NT response forcing. Its main benefit is in slam bidding.
What it buys
In Standard American, 1♠ — 2♣ shows 10 or more points and is forcing for one round. Responder might have 10 points or 19, and opener has to bid the next round without knowing which. Auctions spend their early rounds finding out whether there is a game at all, and often reach the four level before anyone has looked for slam.
Two over one settles that on the first round. Once both players know game is certain, every bid below it can describe shape, extras and controls.
| West | North | East | South |
|---|---|---|---|
| 1♠ | |||
| Pass | 2♣ | Pass | 2♥ |
| Pass | 3♦ | Pass | 4♣ |
| Pass | 4NT | Pass | 5♥ |
| Pass | 6♣ | Pass | Pass |
| Pass |
The forcing notrump
Once the two-level response promises 13 or more, every hand with 6 to 12 points that can't raise partner's major has one bid left: 1NT.
It has to be forcing. Otherwise opener passes it holding a 15-count and a six-card suit, and the partnership sits in 1NT with game available.
Opener's rebids after a forcing 1NT:
- Rebid a six-card major at the two level with a minimum.
- Bid a three-card minor if there's nothing better, so a minor-suit rebid may be only three cards long.
- Bid a real second suit naturally.
- Jump with 18+ to show the extra strength.
Responder then passes, gives preference, or bids again to invite. This part of the system has the most detail, so talk it through with partner before you play it.
When it does not apply
There are three common exceptions:
- By a passed hand. A hand that passed can't hold 12 points, so a two over one by a passed hand is natural and non-forcing.
- After interference. If the opponents overcall, the agreement is off and normal competitive methods apply.
- After a minor-suit opening, in most partnerships. 1♣ — 1♥ is a one-level response and unaffected; whether 1♦ — 2♣ is game forcing is a partnership agreement, and many play it as merely forcing for one round.
Is it worth switching to?
If you play regularly with one partner and you both want to improve, it is usually worth it. Every auction where game is already certain leaves room to find the right game and to explore slam.
If you play with many partners, or casually, it's less clear. Two over one has more auctions that go badly wrong when one player forgets: a forcing 1NT that opener passes, for example, leaves you in a contract neither of you chose.
A reasonable middle path: play Standard American well (sound opening bids and rebids matter more than the choice of system), and switch once you have a partner you discuss auctions with.