Stigma wrote on 10/05/21 at 20:42:55:


As I have been playing the Vienna lately, I would answer 4.Nf3 with 4...d5. Someone who plays the Queen's Indian would probably choose 4...b6. 4...c5 5.g3 is an intricate main line also.

At some point I will have to look at 4.g3, but have not done so yet.

MNb wrote on 09/27/21 at 17:01:41:


You may be right. However I am not aware of any particular problem with either 5...c5 or 5...d5.

A modest back up idea vs 4 Qc2: .. c5 5 dxc5 o-o 6 a3 Bxc5 7 Nf3 d5!?

Originally Ivanchuk - Graf in 2007 but Leela likes it and having updated my database I can see a few strong GMs trying it in 2020/21.

It definitely isn't bad:
8 Bf4 lets black go 8.. Nc6 with a main line 5 Bf4 QGD or try this odd thing: 8 ..d4!? 9 o-o-o Nbd7 10 Na4 Be7 11 Rxd4 Qa5, with the threat of e5 forcing either b4 or Bd2 when white's rook is a bit stranded and the computers seem happy that black has more or less enough play.

8 cd cd 9 Bg5 Be6 10 Rd1 Nbd7 doesn't drop d5: 11 Nxd5? Rc8 is just nasty. 

11 e3 Rc8 12 Bd3 h6 13 Bh4 Bg4?! is Ivanchuk - Graf, 13 .. Qc7 is quite fun, 13.. d4 might even equalise by force and this is so absurdly computerish its impossible to not give it here:
eg: 14 Nxd4 Bxd4 15 exd4 Qb6 16 Qb1 Bb3 17 Rd2 Rfe8+ 18 Be2 Ne4!!? 19 NxN Ba2!! 

Comp main line is then 20 Qa1 Rxe4 21 o-o Bb3.

8 Bg5 might be harder to have real fun against. 8.. Nc6 is sane but slightly lacks the spark you get from a Nd7/Rc8.

Leela wants 8.. dxc4 9 e3 Nd7 10 Bxc4 h6 11 Bh4 which does seem OK for black, but needs care not to get mated by Rxd7. 11.. a6 12 Rd1 Qc7 13 Ba2 Bd6 etc

Maybe too solid if white goes 14 Qd2 here.

There is 8.. dxc4 Bxc4 9 e3 h6 10 Bh4 b5!? 11 Nxb5 Qa5+ 12 Nc3 Ba6/Nd5 which seems risky but maybe..

Dunno

an ordinary chessplayer wrote on 09/30/21 at 14:22:24:


ECO 3 does not even show 9.f3. Row 1 continues with 9.cxd. Footnote 3 with 9Nf3.

I found 5 human games that continue 9.f3 Qh4 10g3 Nxg3 11Qf2 Nf5. The results are split, however engines claim improvements for white.

Emms gave 9f3 an "!". Perhaps TN was warranted as well.

FreeRepublic wrote on 09/30/21 at 13:42:04:

There must be some misunderstanding. 

1.d4 Nf6 2.c4 e6 3.Nc3 Bb4 4.Qc2 d5 5.a3 Bxc3+ 6.Qxc3 Ne4 7.Qc2 Nc6 8.e3 e5 

This is an old and respectable line (also possible from a 4...Nc6 move order), albeit the main move for black is 7...c5. Bagirov in the 1991 ECO (E37) gives 9.cxd5 here; in a note he analyzes 9.f3 Nf6, for example Vidmar - Alekhine, San Remo 1930 (=+). https://www.chessgames.com/perl/chessgame?gid=1007893

I think 7...c5 is a better chance to equalize than 7...Nc6, but 7...Nc6 is certainly playable. 9...Qh4+ is just a mistake.

Next in IsaVulpes' 2016 sharp Nimzo repertoire:

"4. e3 O-O 5. Bd3 d5 6. Nf3 c5 7. O-O Nc6 8. a3 Bxc3 9. bxc3 Qc7"

Gligoric, in his old book on the NID, called this the Khasin variation, after a Soviet master who played it. Ivan Sokolov, The Strategic Nimzo-Indian, calls it the Flexible variation. Black doesn't trade pawns, trying to restrict the scope of white's bishops. This was my choice in 2016 also.

Since that time 8cxd exd 9dxc has come on the scene. Black should either study that line, or try something different. Black could play 6...dxc 7Bxc4 c5 80-0, where he has several reasonable systems from which to choose.

Out of curiosity, what do you prefer to play against the d-pawn specials (and 3.Nf3)?

Considering IsaVulpes' 2016 repertoire after 1. d4 Nf6 2. c4 e6 3. Nc3 Bb4

"4. a3 Bxc3+ 5. bxc3 c5 6. e3 O-O 7. Bd3 Nc6 8. Ne2 b6 9. e4."
This is a standard position and I think gives chances to both sides.

"4. f3 c5 5. d5 b5 6. e4 O-O 7. e5 Ne8 8. f4 exd5 9. cxd5 d6"

I think this was once a side line, but it has been growing in popularity among theoreticians. It does well in practice too!

It was recommended for black in Dangerous Weapons NID, later Sielecki recommended it in his Nimzo/Bogo Opening Repertoire. GM Kuljasevic provides two answers to 4f3 in his Nimzo eBook at Modern-Chess, and this is one of them. As an aside, I like Kuljasevic's book very much and will refer to it again.

The line is very sharp. Black can also play 6...d6.

MnB mentions 4.f3 c5 5.a3 Bxc3+ 5.bxc3, and also 4.a3 Bxc3+ 5.bxc3 c5 6.f3 which transposes to the same position. Good point.

Here 6...d5 is main line theory. However some theoreticians have advanced 6...Nc6 instead. At first it looks like white is getting his way with 7e4. After 7...d6 black asks "what now?" It's not clear that white has a great answer. I recommend Kuljasevic once again.