The origin of this conventional method is unknown. It is, however, a feature of the Acol bidding system generally used in the United Kingdom as an opening bid to describe a certain holding with length in both Minor suits. The 5 No Trump bidder holds also only one losing trick in one of these two Minor suits.
Note: The holding of the bidder guarantees game in a Minor suit. The question is whether the responder can cover the one losing trick in order to be able to bid with assurance the grand slam.
Note: In comparison to the 4 No Trump opening bid is not a preemptive opening bid, but rather inquires about the number and/or the location of the Aces held by the responder.
Note: This conventional opening is also categorized among preemptive opening bids, since any competition seeking a fit in either Major suit must enter the auction on the six level.
The opening bid of 5 No Trump is forcing for one round. The partner must bid, and the requirements for the responder is that the responder bids the better Minor suit one level for each Ace, King, or Queen in his holding. The responder does not bid the Minor suit, in which the honor is held but rather bids the lower-ranking Minor suit to show a held honor.
The following illustration clarifies this concept:
Example 1
| Opener |
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Responder |
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Meaning |
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| 5 No Trump |
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Promises a holding containing both Minor suits, and a maximum of 1 losing trick in one of the Minor suits. Note the difference in that the definition is not that the opener has 1 Losing Trick in each of the Minor suits. |
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6  |
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The responder promises the possession of the King of Diamonds. The responder does not bid the Minor suit, in which the honor is held, but rather bids the lower-ranking Minor suit to show a held honor. |
7  |
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The opener knows that the missing King of Diamonds is present in the holding of partner and bids the grand slam in Diamonds. |
The opener realizes that the holding contains only one losing trick and must discover whether the responder / partner may possibly possess the King of Diamonds for the grand slam. As soon as the opener is informed by the responder that the responder does indeed hold an honor in one of the Minor suits, then the opener bids the grand slam if the King is held.
Note: If the opener holds the King of Hearts, then this card is also a losing trick and the opener bids only the small slam in Diamonds, the longer Minor suit.
Note: In the original version of this conventional method the responder, holding the King of Diamonds as in the Example 1, first bids 6 Clubs to show a held honor in one of the Minor suits. The relevancy of any held Ace and/or King in either Major suit becomes unimportant since only one of the Minor suits will constitute the final contract. However, if the responder indeed holds both Aces in both Major suits and an honor in one of the Minor suits, then the responder will first show the honor in the Minor suit allowing the opener to show a preference, which then leaves the option open to the responder to either pass of bid the grand slam in No Trump.
Example 2
| Opener |
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Responder |
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Meaning |
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| 5 No Trump |
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Promises a holding containing both Minor suits, and a maximum of 1 losing trick in one of the Minor suits. Note the difference in that the definition is not that the opener has 1 losing trick in each of the Minor suits. |
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6 |
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The responder promises the possession of an honor in the Diamond suit. The opener knows that it is the Ace of Diamonds. The responder does not bid the Minor suit, in which the honor is held, but rather bids the lower-ranking Minor suit to show a held honor. |
| 7 |
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Since the holding consists of only both Minor suits, then the grand slam in Diamonds is secure. The declarer can only wish for a favorable split in Clubs. |
Again the opener has a holding, which contains only one losing trick and must discover whether the responder / partner possesses an honor in one of the Minor suits.
Note: Since the partner knows that the opener holds both Minor suits, then the partner will bid the small slam without an honor in either Minor suit and bid the grand slam with a honor in either Minor suit.
Variation for Major Suit and Minor Suit
This concept has been varied to include a two-suited holding with a Minor suit and a Major suit. The modification is that the opener bids 5 No Trump showing only one losing trick. The partner assumes that the opener holds both Minor suits and only one losing trick and bids at the seven level holding the necessary cards for both a Minor suit and a Major suit grand slam.
If the responder, on the other hand, holds only a Minor suit honor, then the responder bids 6
or 6
, which informs the opener to pass with a Major suit and continue to bid the grand slam with the Minor suit.
Variation for All Suits
A second variation of this concept is that the opener can show any two-suited holding by opening with 5 No Trump. Promising a holding with only one losing trick, the responder can communicate the following with individual bids outlined below:
| 6 : |
Promises no Ace or King in Clubs. |
| 6 : |
Promises an Ace or King in Clubs but not in Diamonds. |
| 6 : |
Promises an Ace or King in each Minor suit. |
| 7 : |
Promises an Ace or King in three suits. |
If you wish to include this feature, or any other feature, of the game of bridge in your partnership agreement, then please make certain that the concept is understood by both partners. Be aware whether or not the feature is alertable or not and whether an announcement should or must be made. Check with the governing body and/or the bridge district and/or the bridge unit prior to the game to establish the guidelines applied. Please include the particular feature on your convention card in order that your opponents are also aware of this feature during the bidding process, since this information must be made known to them according to the Laws of Duplicate Contract Bridge. We do not always include the procedure regarding Alerts and/or Announcements, since these regulations are changed and revised during time by the governing body. It is our intention only to present the information as concisely and as accurately as possible.