I was playing the other day at a club game in Trail, and an opponent opened a Mexican Two Diamonds with 18 to 19 points and a singleton Spade. Following the correct system, the bid should show a balanced 18 to 19 points. The hand fell apart when the partner, expecting the opener to have two Spades, tried to play in a six-card Spade suit.
Even if both partners know the Mexican system well, I prefer a weak Two Diamonds because it is more frequent and it takes away a bidding level when the opponents are likely to enter the auction.
If one partner has 18 and the other has zero points, would one rather be in one of a minor or in a contract higher than Two Diamonds? Opponents may balance over one of a minor which shows 12 plus, but will be reluctant to do so when an opponent is known to have 18 or 19.
The bidding: The hand above occurred in the team event of a Spokane Lilac Sectional. Because I was using Mexican Two Diamonds, I could not open a weak two diamonds and my partner and I missed a biddable slam. Our teammates were not impressed and told me that something good should come out of the bid for which we gave up a weak Two Diamonds. I could not think of anything.
A lot of the alternate uses of Two Diamond openings, other than a weak two, get the partnership too high when the partner is bust, and a description of the hand by standard methods turns out to be much better.
Over weak two’s, I like to use Two No Trump asking for a possible side entry (a feature) and Three Clubs asking for shortness (a singleton or void). Here the shortness is a Spade singleton.
North cuebids his Club void and South cuebids his Heart control. North has enough information to bid Six.
The Lead: King of Clubs although a low Spade is a good candidate for a lead.
The play: Declarer ruffs the club with the Queen of Diamonds, goes to the King of Hearts, ruffs another Club with the Ace of Diamonds and plays a small Diamond to his hand. Declarer will get two Club ruffs, five Hearts and six Diamonds making Seven. The opponents can keep declarer to Six by leading a Spade.
Result: Six Diamonds plus one for +940.