28. Two Diamonds Conventions

The weak 2♦ opener doesn’t get much respect these days – the chances that you’ll end up playing it are not that great, since either opponent with a good holding in a major suit is able to get in relatively cheaply. Therefore, the bid has been co-opted to handle various other problems, particularly awkwardly-shaped hands.

Note that Precision has its own two-diamond opener showing a 4441 hand, 11-15 HCP with a stiff diamond. There are many other two-diamond bids. Some of them are strong.


When you hear a 2♦! opener alerted, you have no idea what it means. Ask if you need to know.

The so-called Multi-2♦ is a particular headache – it is not allowed in most ACBL tournaments, but you can encounter it online.

It is also worth saying that if an opening 2♦ isn’t strong or Flannery or a three-suited hand of some sort, or you see any other bid that seems to mean too many things at once, you might want to call the director to inquire about it. Twice I’ve caught people playing an illegal convention this way.

Flannery 2♦

The Flannery 2♦!(5 hearts, four spades, 11 to 15 HCP) opener covers a hand with five hearts and four spades and values insufficient to reverse on the second bid. Obviously, you lose the ability to make a weak 2♦ opener.

If you open 1♥ then responder will assume you do not hold four spades, and in particular 1♥ - 1♠ shows five spades.

The responses are:

  • Pass can be made with a six card diamond suit and fewer than 10 HCP.

  • 2♥ and 2♠ are to play.

  • 3♥ and 3♠ are invitational.

  • 4♥ and 4♠ are to play.

  • 3N is to play.

  • 2N! inquires about opener’s minor suits. The bid is one-round forcing. Responses are:

    • 3♣ shows a 4=5=1=3 shape.

    • 3♦ shows a 4=5=3=1 shape.

    • 3♥ shows a 4=5=2=2 shape, minimum.

    • 3♠ shows a 4=5=2=2 shape, maximum.

    • 3N shows a 4=5=2=2 shape, both minors stopped.

    • 4♣ shows a 4=5=0=4 shape.

    • 4♦ shows a 4=5=4=0 shape.

A sequence such as 2♦!-2N!-3♦!-3M would be invitational, not forcing.

There are also these special responses:

  • 3♣ shows at least six clubs, to play.

  • 3♦ shows at least six diamonds, invitational

  • 4♣ and 4♦ are transfers to 4♥ and 4♠ respectively.

    These transfers are the power raises, giving responder a chance to start slam bidding. Opener will complete the transfer with a minimum, or bid the intermediate suit with a maximum. These bids are made with slam interest, with responder able to bid RKC with 4N next.

Note: some partnerships allow Flannery on a 4=6 shape as well.


A mini-Roman 2♦ opener is a 4441 or 4405 hand, 11-15 HCP. The most frequent agreement seems to be that the bid promises 4 spades – the 1=4=4=4 hand being handled by opening a diamond; but that is not universal.

Lacking invitational values, the responder will suggest a place to play, bidding up-the-line; only rarely will responder pass with a long diamond suit.

With invitational values or better, responder bids 2N! asking opener to bid his short suit. This is forcing; responder next places the contract in game or makes an invitational bid in a suit.

The mini-Roman is part of a family of Roman 2♦ bids which chiefly differ as to strength. A Precision player’s 2♦ opener means explicitly a diamond shortage but NOT a 4=4=1=4 shape necessarily.

Mexican Two Diamonds

Named after its author, George Rosenkranz of Mexico, opening 2♦ shows a balanced 17 to 19 HCP. Responder bids:

  • Pass with a weak hand but five+ diamonds

  • 2♥! shows fewer than 7 HCP so opener places the contract, usually at 2N.

  • Otherwise responder relays with 2♠! to 2N, and systems are on, including Texas transfers. Game forcing.

Most often this convention is played with a weak notrump system.

Much more complicated versions exist. Be sure to ask for an explanation if on defense.

Other Meanings

2♦ openers were strong in the days of Goren, but that was superseded by the use of 2♣ as the sole strong opener.

If you are facing a pair playing a strong 1♣ system, such as Precision, a 2♦ opening will be either an intermediate (11-15 HCP) bid short in diamonds with no four-card major, or it can be a strong bid.

A responder bid of 2N! shows a strong hand, and inquires about the opener’s shape.

Defending against such systems, it is important to discuss beforehand what 3♦ means and what double means (penalty, or takeout, or lead-directing?). Generally a double of an artificial bid would be lead-directing unless you agree otherwise.

The “could be short” meaning “as few as two” announcement of a 2♦ bid is your warning to check their card. Some Precision pairs do not even promise two diamonds, and they should alert that not just announce it.

Multi Two Diamonds, a two diamond opener showing a preempt in an unknown major, is now legal in ACBL Open+ Chart Events (typically, 2-session Regionals and NABCs). You may encounter it, or its full monster sister that might also be a strong 4441 or NT hand, online or in other jurisdictions.