Gazzilli

I haven't posted anything on Gazzilli before. It's one of my favorite conventions which occurs when the auction starts 1M-1NT or 1♥-1♠. It's a very simple convention with big advantages, few disadvantages, and it comes up frequently.

A 2♣ rebid from opener is a 2-way bid, showing one of 2 hand types:
- 16+HCP, any distribution
- <16HCP, natural (or semi-natural if that fits your system)

Responder has only 1 strong response: 2♦ shows 8+HCP, any distribution. Any other bid shows less than 8HCP and is natural. In this case a preference should be given to a doubleton Major support.

Opener will now clarify which hand type he's holding:
- After 1M-1♠/NT-2♣-2♦, opener rebids 2M with the weak version. Any other bid shows 16+HCP and makes the auction GF. Bidding 2OM usually shows a 3 card suit, which makes finding 5-3 and 6-2 fits a lot easier.
- After any weak bid, opener will usually pass with the weak version. With 16-17HCP and misfit he'll also pass. With a very strong hand he can bid a new suit. With fit he can still invite or bid game.

Basic structure after 2♣:
2♦ = 8+HCP
...2M = <16HCP, (semi)natural ♣
...2OM = 16+HCP, any hand with 3OM
...2NT = 16+HCP, balanced, no 3OM
...3m = 16+HCP, natural, no 3OM
...3M = 16+HCP, natural, no 3OM
...3OM = 16+HCP, 4OM
2M = <8HCP, 2-3M
2OM = <8HCP, natural, 0-1M
2NT = <8HCP, minors, 0-1M
3m = <8HCP, natural, 0-1M

There are some specific exceptions:
1♥-1NT-2♣-2♠ = <8HCP, 3♠ (1NT already denied 4♠) and both minors (5530 or 5431).
1♥-1NT-2♣-2♦-2♠ = 16+HCP, 4♠ (showing 3♠ is useless).

Obviously you can modify this structure a bit, for example use 1♠-1NT-2♣-2♦-2♥ to show 3-4♥. As a result, 1♠-1NT-2♣-2♦-3♥ will now show 5♥.
You can also use 1M-1NT-2♣-2♦-2OM as various handtypes (this saves space!).
If you play Kaplan inversion, it also has implications to rebidding 2OM after a 1♥ opening.

As usual there are a few (pretty rare) problem hands: <8HCP with 1=4=4=4 and the auction starts 1♠-1NT-2♣. Usually it's best to just bid 2♥ and hope for the best. Another one is after 1♥-1♠, when responder has a strong hand you may have some difficulties.

Playing Gazzilli frees up a few rebids for opener:
- Jump rebids (like 1M-1NT-3m) show a 5-5 with 2 great suits but less than 16HCP. If responder has honours in both suits, 4M in a 5-2 fit can be possible. A typical example is AKxxx-AQxxx opposite Qx-Kxx. 10 tricks are for the taking if both suits behave a little bit.
- 1♥-1NT-2♠ shows a minimum hand with 6♥-5♠.
- 1M-1NT-2NT: you can use this to show a GF hand with 6M-4m. Since these are difficult to bid anyway, you might as well make it easy using this tool.

In my current 2/1 system we play Gazzilli. The weak version can be with only 2♣s (5M332 or 4=5=2=2) because we prefer to have our 2♦ rebid natural with 4+ cards. Only exception we have to the 2♦ rebid is when we have 4=5=3=1 exactly. Playing 2♦ or 3♦ is acceptable since we have true ruffing value.

A new approach (2)

2/1 GF except rebid is imo the way to go. Playing jumps as invitational loses too many options, and bidding 1NT with an invitational good 6 card suit can sometimes make it difficult to show your true strength later on. It also makes a semi forcing 1NT response possible, which can be a winner over forcing 1NT.

However there's always that 1 difficult auction: 1♠-2♥. With my new partner we respond as follows:
2♠ = any minimum without 4♥
2NT = 16+HCP, no singleton or void, not 4♥ (so 5332/54m22/6322/7222)
3m = 16+HCP, 4+m (not 5422, not 3♥)
3♥ = 16+HCP, 4♥ / 3♥ + singleton/void
3♠ = 16+HCP, 6+♠, 0-1♥, no side suit
3NT = not used!
4m = minimum, 4♥, 0-1m
4♥ = minimum, 4♥, 5422

3NT isn't used, but a useful agreement could be 5=4=2=2 with values in the short suits.

The 2NT rebid is a little homegrown tool, useful to find 6-2 or 5-3 ♥ fits while you know opener doens't have immediate ruffing value. This also makes our 3♥ rebid better defined: it always shows potential either by ruffing value or because of an extra trump.

After 1♠-2♥-2♠ (this is forcing for 1 round btw - opener can have up to 15HCP and can still have a 3 card ♥ fit), responder can just rebid 3♥ to show the invitational variant. With a GF responder can bid natural (except 3♥), or use 2NT as a relay to ask about opener's shape.
After any other rebid from opener the situation is GF.

There is 1 hand which may be difficult: opener is minimum, and responder has a GF with 6♥ and no ♠ fit. In this case, you can't find a 6-2 ♥ fit.

These days some pairs reverse the meaning of 2♦ and 2♥ responses over a 1♠ opening, to avoid similar problems. Although it has merit, it also brings many problems.
- For starters, there's no well defined structure after 1♠-2♥ showing ♦ (as an example, in IMP magazine there was an article on the switch: a few pages on continuations and theory after 2♦, and just one column on 2♥). Opener lost a lot of valuable space! Should he still be looking for a ♥ fit? Should he support ♦ with minimum hands? Etc. In my previous post I mentioned that we have described our 1♠-2♦ very well (usually 6+ cards), so we could get away with the switch.
- On the other hand, 1♠-2♦ (showing ♥) isn't perfect either. Do you want to be able to stop in 2♥ or not? If so, you'll need to find a way to show your 14-15HCP hands with 3 card support. But this will make things harder to support when you have 18-19 with a 4 card support! So while you're creating more space, you should actually give up on being able to play 2♥ and use this to show minimum hands with 2-3♥.

My conclusion on the switch is mainly that it doesn't fit well in a "2/1 GF except rebid"-structure. If 2/1 is an absolute GF, then it may make sense. I've also seen people include weak hands with 6+♥ instead of invitational ones. This is probably playable, since 2♥ rebid from opener isn't forcing anymore, but probably brings up some problems elsewhere in the system.
Either way, since you have to give up a lot (response structure + 1♠-2♥ continuations), it's imo not worth the trouble.