What does partner show with their bid?
A big double hand (Super overcall), meaning 17-20 points and 5+ cards in Spades.
With 9-16 points, partner would've overcalled 1♠. As overcall is limited to up to 16 points, and partner has more, they need to double 1st, then bid their suit to show a stronger hand.
Note that if partner has a normal double bid (12-16 points) they would've passed your 2♣ which limited your hand to 0-8 points.
Because partner's is strong, your hand is worth inviting. Partner will have to decide whether to accept and raise to 4♠ or to Pass.
The possible hands:
You can see here that 4♠ can make with an overtrick. Partner has a maximum hand and great Clubs to your bidden suit.
Here, 4♠ can also make. Partner has 6 trumps, valuable aces, and a useful ♣K.
In the above case, partner will choose to pass estimating the points as less valuable. They have minimum, balanced, wasted values in Diamond, and fewer controls.
Note:
a. A Take out Double followed by a new suit is showing a big double hand, meaning an overcall shape hand but with 17-20 points (big double or super overcall).
b. With a stronger hand than that, your 2nd bid should be a cue bid (double and then cue bid) which normally shows a game forcing hand.
You have a huge hand and should be thinking about slam. More clues are needed about partner's hand before making a decision on slam or whether to settle on game. Also, the final contract doesn't have to be in Diamonds.
Partner's hand could be:
a.
You can see that a slam in Spade looks very possible while a game in Diamond or NT isn't at all sure.
b.
Here, 3NT would be best
c.
In this case, 6♦ is laydown.
d.
In this hand, 7♦ is laydown.
Therefore, you need to find a bid which will show strength, force partner to bid, describe your hand, and be below the 3NT level.
Any rebid in your suit or partner's suit on 2 or 3 level is non forcing (same for 1, 2, or 3NT). The only forcing bids here are 2♥ (reverse) and 3♣ (jump shift).
Bid 3♣. You don’t have 4 cards in Club but a jump shift is game forcing. Even if partner will support Clubs, you still have escape to Diamonds to describe your hand (no other way to describe it). That is a fictive jump shift which is used when you have very powerful hands which can't be described on a 2nd bid.
You can try 4NT, but then you still don’t know enough about partner's strength and distribution, nor if partner has anything in Diamonds.
Note:
a.
1♦ ------ 1♠
3♣ = Jump shift, game forcing, showing 18-21 point. It's normally a natural bid, showing at least 5-4 in the minors, but that bid could also be a fictive jump shift in order to keep the bidding low and force partner to bid on. That's the most suitable bid for this hand.
b.
1♦ ------ 1♠
3♦ = shows 15-17 points with 6 cards in Diamond and can be passed by partner, which is why it's not a good bid here.
c.
1♦ ------ 1♠
3NT = shows 6-7 cards in Diamond and a game forcing hand. Could be a good bid if partner bids 1♥. But here, it's not so effective. We could have a slam in Diamond (or Spade) while 3NT goes down (partner could pass with no Heart stopper and a balanced hand whilst having some Diamonds).
d.
1♦ ------ 1♠
4♦ = This bid shows 6 strong cards in Diamond and 4 cards fit in Spade.
e.
Note that a 2♣ opening was possible in this hand, but would be very hard to then describe the hand later or find out more about partner's hand, example:
2♣ ------ 2♦
3♦ ------ 3♠
You play 5♣ and West leads the ♦3. You take East's ♦Q with your ♦A. How will you continue?
You have 5 losers: 1 Spade, 1 Heart, 2 Diamonds, and 1 Club.
2 Diamonds can be ruffed in dummy. A 3rd loser must disappear from either a successful finesse in Club or by promoting a Spade trick on which you can discard your Heart loser.
Your best chance is to play your spade right away towards the ♠K. If West takes the ♠A, your ♠K will be promoted allowing you to discard your Heart loser. Then, when you ruff 2 diamonds and discard a Heart on the ♠K, you'll manage just 2 losers (♠A and ♣K) although the Club finesse loses.
If you ruff a Diamond at trick 2, you might go down as you don’t have a fast entry to your hand to play the Spade finesse. For example, after ruffing diamond, you try the Club finesse from dummy. West will take the ♣K and play another Club, and now you can't ruff the next Diamond.
The same will happen if you play Club to the ♣A and then Spade. West will take the ♠A, the ♣K, and you'll be unable to ruff 2 Diamonds in dummy.
If you ruff a Diamond and play spade from dummy at trick 3, you won't be able to promote a Spade trick as cards lay (♠A is 4th).
Note:
a. Playing Spade at trick 2 will bring success even if the ♠A in East. As long as Spades are 4-3 and Clubs 2-2, you'll be able to promote your 5th Spade for a Heart discard. Say your ♠K loses to the ace in East, then East continues with Club. You win with the ♣A, ruff Diamond, ruff the 2nd Spade in hand, ruff Diamond, ruff the 3rd Spade in hand, play Heart to the ♥K, ruff the 4th Spade, then play a Trump to pull out opponent's last trumps. Your 5th Spade is high now, and the ♥A is an entry to it.
b. The above bidding uses SAYC. If playing 2/1, you need an agreement on how to bid South's hand. You can agree that a jump to 3♣ is showing 10-11 points with 6 cards in Clubs. But if 3♣ is Bergen raises, then you'll need to either upgrade your hand for a 2♣ game forcing bid or bid a 1NT (1 round forcing) planning to bid 3♣ later showing a relatively weak hand with long Clubs.
Thanks. Very educational. Very smart.
If you return a spade, declarer takes the spade queen, 3 hearts and 6 diamonds for 10 tricks before partner gets in the with club ace.
I think I'm correct in Hand 3 to lead a spade to set up my partners spades and he has an Ace Club entry.