Overcalls over their 1NT
It's not always clear whether to bid after an opponent opens 1NT. You're sometimes worried about coming into the auction because the 1NT opener has shown a strong balanced hand. There are lots of conventions around to allow you to bid here, and especially to show single-suited and two-suited hands. It's important to be able to show a hand with both majors too. The Cappelletti Convention is the one I'll discuss here. You need 10+ points to use this convention, and values in your long suits.
Some principes to follow:
When your hand is two-suited, and you have a bid to tell partner this, do it, because partner will be able to prefer one of your suits.
Defending 1NT is not in your best interests if you are two-suited, or single-suited. These hands declare better than they defend, because you have your own long suit/s, and the opponents usually have the other two suits.
With 5332 shapes, and around 11 points, it is usually better to pass, and defend 1NT.
You're generally not trying to get to game, so be happy to find a partscore, as one opponent has 15 - 17 points.
With a hand that merits action, proceed as follows in both the direct seat and the balancing seat.
Double is for penalties (shows a hand in the higher range of the 1NT opener)
2♣ shows a single-suiter
2♦ shows both majors
2♥ shows hearts and a minor
2♠ shows spades and a minor
2NT shows both minors
RESPONDING TO CAPPELLETTI
If partner doubles their 1NT, leave it in unless you have a very weak hand with a long suit (bid 2 of your suit)
If partner bids 2♣ showing a single -suiter, respond 2♦ and partner will tell you which suit they hold
If partner bids 2♦ showing at least 5/4 in the majors, pick the major you prefer, based on trump length, and decide the level, eg if you have 4 trumps for partner, jump in that suit, regardless of points
If partner bids 2♥ showing hearts and a minor, with heart support, pass or raise hearts. With the minors, bid 3♣ (pass or correct)
If partner bids 2♠ showing spades and a minor, with spade support, pass or raise spades. With the minors, bid 3♣ (pass or correct)
If partner bids 2NT showing both minors, bid your longer minor
Finer Points for Experienced Partnerships
If the opponents open 1NT, and their partner passes, it is likely that your side has around 20 points (could have from 16 – 25). So, if the bidding goes 1NT P P to you, and you hold 9/10 points, your side might have the balance of power. With 5/4, or a single-suiter, try to find a bid. Relax the Cappelletti requirements a little here, but it’s not recommended on 4/4's. These hands are better defending.
(2) Balanced Hands:
With 5332's, and around 11 points, it is usually better to pass and defend 1NT. The best hands for Cappelletti are single-suited (ie 6+ cards), or two-suited (5/5, or 5/4) because these hands will not defend well.
(3) Passed Hands:
Partner will know you have fewer values, or something not good enough to bid at first, eg if you show a single-suited major after the bidding goes P P P 1NT (2♣) p 2♦ p 2♥/♠, partner will know your suit wasn't good enough to start with a weak two-bid.
(4) 2NT invitational by Advancer:
If partner shows a hand with hearts/spades and a minor, bidding 3♣ by advancer is called “pass or correct”. This means there is no major fit, and you’re asking partner to show which minor suit they hold. You will pass the response. BUT, if you have a better hand, (invitational), and are interested in game, start with 2NT instead. It also asks the overcaller about the quality of their hand. So, if the bidding goes 1NT (2♠) p 2NT p 3♣/♦ this shows a minimum, but if the overcaller is better, it will go 1NT (2♠) p 2NT p 3♥/♠ = better hand with clubs (3♥) or diamonds (3♠).
This plays a part in all your decisions about entering an auction that has started with 1NT. Be more cautious when vulnerable, as your side may go for a number (large penalty) if you pick the wrong time!
Want more information? This book will help you with overcalling their 1NT opening.
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