As I looked at 13...Qh4 as a winning try some remarks:

Iso 25...b4 26.cxb4 Bxd3 Black might play 25...Bxd3 26.axb5 (26.Bd2 Be4 27.Qd4 fxg3) fxg3 27.Nxg3 (27.hxg3 Be4 28.Qg5 Qf7 and it's still a game) Bxb5 though White can spoils the fun with 28.Be3.

After 22.a4 Black may try b4 23.cxb4 Bd5 24.Bd2 Rf8.

21.Be4 has more recently been played in De Souza-Menendez, corr ICCF 2005. Black also won this one.

Perhaps, if Black is desparately looking for a win, 18...Kh8 is an option. After 19.Bxd5 cxd5 20.Bf4 Be7 play is quite complicated due to the insecure position of Rd4.

Markovich wrote on 04/09/11 at 16:05:58:

How exactly is White supposed to refute 12.d3 Bd6 13.Re1 Qh4 14.g3 Qh3 15.Re4 Qf5 16.Nd2 Qg6 17.Re1 f5 ?

And if White can't, doesn't this provide more winning chances than 13...Bf5 ?

Markovich wrote on 04/10/11 at 14:08:32:


I looked a bit at 18.a4, 18.c4 and 18.f4 and I found the complications amazing.
After 17.a4 Black can choose between 17...Nf6 and 17...Bf5.
17.Nf1 f5 18.Rd4 f4 looks attractive.

A search in Megabase for games in the years from 2000 to 2010 with the rating of both players between 2000 and 2300 indicates that the Marshall is a viable choice since Black scored 52%.

In my experience even strong players are not always well prepared or decide to deviate early for some reason. An example from my own praxis are two games from last year (one against an IM) where my opponents played the rare 1.e4 g6 2.d4 Bg7 3.Nc3 d6 4.f4 Nf6 5.Nf3 c5 6.d5 with White against me (I won both) but no one dared to play 6.Bb5+ which is the mainline.

If you like the resulting positions arising from the Marshall I see no reason not to give it a try but like belgian I expect most players to deviate before move 8 with the Marshall rarely appearing on your board.

Fllg wrote on 04/10/11 at 07:32:12:


Yeah, I looked at both of these before posting about ...Bb8, actually.  But I think you're right.  So now the question is, is Vigorito right that 18...Qh5 19.Be3 Bh3 is viable for Black?  It certainly is a lot more appealing than 19...Bxd3, which Vigorito doesn't like (I have Brunello and Pavlovic by the way; all I lack that's recent is the Gustafsson DVD).

But leaving aside 12.d3 there is the larger question of whether the Marshall is a good repertoire choice for someone in the lower-to-middling range of "strong" players, say a USCF-NM?  I would argue that at lower levels it might be (if anyone ever got a chance to play it), because White's theoretical knowledge might permit Black a decent proportion of wins.  One you get to the Open Section of a decent weekend Swiss, however, you're up against people who are likely to know some theory, and the question becomes, can you play this for a win, or perhaps more correctly, can you expect your white opponents to screw up that often?

Hmm, perhaps yes.

Anyway I would concentrate my investigations on Gustafssons 14... Qf6 if I intended to play the Marshall with Black.

Edit:

Upon further reflection Black seems to be okay here as well.

I) 25.Rad1 f4 26.Bxf4 Rxf4 27.Rd2 (not 27.gxf4 Bxf4 -+) Rf5 28.Qb6 Rdf8 29.f4 Qg4 with good play.

II) 25.Qa4 f4 26.Bxf4 Rxf4 27.Re2 (here 27.gxf4 Bxf4 is bad as well for White) Rf7 with counterplay based on Rdf8, h5-h4, Ba7. It will take quite some time before the queenside pawns become dangerous, e. g. 28.Qc2 h5 29.d4 h4 30.c4 hxg3 31.fxg3 Rdf8 32.Rg2 Qf5 33.Re2 Qh3 repeats.

Of course in these lines many other moves can be considered...

MNb wrote on 04/09/11 at 18:46:34:


I think actually it was 23... f5 24.Qxb5 Bb8 when your 25.Bb6 leads to this position if I´m right:



But here silicon suggest 25... f4! with a clear Black advantage.  

Possibly 25.Bc5 f4 26.d4 fxg3 27.hxg3 Bxe4 28.Rxe4 Bxg3 29.fxg3 Qxg3+ with a perpetual is the best.

Some confusion with moveorders and numbers here. I hope I got it right this time. 

Markovich wrote on 04/09/11 at 16:45:21:


Markovich wrote on 04/09/11 at 17:11:30:


You got your moves mixed up again. Assuming you meant 24...f5 25.Qxb5 Bb8, here 26.Bb6 looks annoying.
So either 25...Ba8 25.Rad1 f4 26.Bxf4 Rxf4 27.Rd2 or 25...Bc7 25.Rad1 f4 26.Bxf4 Bxf4 27.c4 and in both cases I don't see how Black can make progress.

I also must say that the way Black shifts Bishop (Bc8-f5-h3-e6-d5) and Queen (Qh4-h3-h5-h3) strikes me as a bit odd.

Luis Almiron played in WCh-23 finale, ICCF 19...Bxd3 20.Nd2 b4 and drew against RJ Maliangkay. Later he won a game with it. So this deserves attention.