Choice of Opening Defines Contract

One of my students sent me this hand from a recent online Pairs event.

You are vulnerable against non-vulnerable opponents and there are two passes to you. What do you open?

The danger of opening 1D which, technically, seems the correct bid, is that your opponents might bid some number of a major suit and you will end up either being outbid or forced to play in diamonds. If your partner has 6-8pts, he may not be able to show clubs and 3NT may be missed.

What about 2D? Asssuming that you don't play it as a third Weak 2 (such a bad idea IHMO), but instead as a Strong 2 in one of the four suits, again there may be a problem showing clubs. Although most pairs play Stopper-Showing Bids after the sequence 2D - 2H - 3D - there is no room here to show clubs.

All in all, despite its obvious shortcomings, an opening of 2NT seems best. Fine if you play 19-21, or 20-22, it is possible that 5D will play better than 3NT but, even if it does, your opponents may be more tempted to lead a major suit.

At Pairs scoring, 2NT looks best.

Partner's hand was: s xx h xxx d xx c AQJxxx

Having opened 1D, E/W competed aggressively to 3H. Partner was shut out of the auction and 4D became the final contract, which just made. Unfortunately, 3NT was easy...