Hand 13 - 1NT vs 1 Major

This is chapter 13 in the story of my attempt to determine if it is better to open 1♠ or 1NT with 15 to 17 HCP and a five card ♠ suit.

The journey started with this post:
Later On

Here is the thirteenth hand I generated:

	North ♠AQJ85 ♥AJ3 ♦QJT ♣52
West ♠KT73 ♥8742 ♦963 ♣84		East ♠92 ♥K9 ♦K2 ♣KQT9763
	South ♠64 ♥QT65 ♦A8754 ♣AJ

Dealer is North and everyone vulnerable.

Double Dummy:
6♦ can make by N/S
5♥ can make by N/S
4♠ can make by N/S
3NT can make by N/S

Analysis

If North opens up 1NT I think East will probably show their ♣ suit by bidding 2♣. Some might have to "Double" to show a single suited hand. Whatever they need to do to show a single suited hand they will do.

South will bid Stayman in however way the partnership has agreed to do that.

Some play stolen bids so "Double" of 2♣ is now Stayman.

Some play cuebids so 3♣ by South now asks North if they have a four card major.

Of course if they are able to South can always bid 2♣ (Stayman) -- this really depends on what East has bid.

In any case the partnership will probably land in 3NT.

What happens if North opens 1♠?

If North opens up 1♠ I think East will show their ♣ suit by bidding 2♣.

South can make a Negative Double to show the other two suits.

North is kinda stuck over the Double. They can't bid NT because they don't have the ♣ stopper. But they will have to bid. So they will bid either 2♦ or 2♥. I'm quite confident that the better players would bid 2♥ because they are not worried about a possible 4-3 fit. They know they are trumping in the short side. Plus Partner could have a five card suit.

If North bids 2♥ South will bid 4♥. Which actually does better than 3NT even though they do not have an eight card fit! Even if South (with only 11 HCP) just invites with 3♥, North should bid the game. They are more than their minimum for sure.

If North bids 2♦ South will bid 3NT since they have the ♣ stopped.

Will they reasonably make the contract? Is the Double Dummy accurate?

In 3NT North just has to hold up once on the ♣ lead. Then they have to do the obvious ♦ finesse. That will get them eight tricks. For their ninth trick they have to choose to finesse the ♠ rather than the ♥. This one is not so obvious because both will allow East to win the trick.

In 4♥ things are a little safer. Declarer MUST finesse the ♥ (which loses and will take you down if you are in 3NT) but the good thing here is that East cannot run their ♣ suit. North can trump!

So in the end I think most roads lead to 3NT (which does depend on a good guess to make) however the one road that leads to a better contract (4♥) is the road that starts with 1♠.

Plus by some fluky "All My Finesses Win" thing N/S do happen to make 6♦. They probably have a better shot of getting there over 1♠. I don't think they will but they have a better shot.

So I am giving 1♠ the win.

To see the table where all the hands are listed click HERE!