Originally posted by wormwood
really? what's so dubious about it? I haven't played agains QGA in a couple of years, and I didn't know it well back then either.
Well, from my very own dubious understanding of the opening, if black is ever planning to try to hold on to the extra pawn with b5, he has to show something up for white's a4. White's a4 usually doesn't work when Nc3 has been played as b4 simply kicks away the knight, and even worse, if e4 and Nf6 has already been played this means the e pawn is going to fall.
In the game you've posted for example, white doesn't have a4 because the e pawn hangs. The same thing in here with anand-kramnik (I recently played a game in this line):
[Event "WCh"]
[Site "Bonn GER"]
[Date "2008.10.26"]
[Round "9"]
[White "Anand, V."]
[Black "Kramnik, V."]
[Result "1/2-1/2"]
[ECO "D43"]
[WhiteElo "2783"]
[BlackElo "2772"]
[PlyCount "90"]
[EventDate "2008.10.14"]
1.d4 d5 2.c4 e6 3.Nf3 Nf6 4.Nc3 c6 5.Bg5 h6 6.Bh4 dxc4 7.e4 g5 8.Bg3 b5 9.Be2 Bb7 10.Qc2 Nbd7 11.Rd1 Bb4 12.Ne5 Qe7 13.O-O Nxe5 14.Bxe5 O-O 15.Bxf6 Qxf6 16.f4 Qg7 17.e5 c5 18.Nxb5 cxd4 19.Qxc4 a5 20.Kh1 Rac8 21.Qxd4 gxf4 22.Bf3 Ba6 23.a4 Rc5 24.Qxf4 Rxe5 25.b3 Bxb5 26.axb5 Rxb5 27.Be4 Bc3 28.Bc2 Be5 29.Qf2 Bb8 30.Qf3 Rc5 31.Bd3 Rc3 32.g3 Kh8 33.Qb7 f5 34.Qb6 Qe5 35.Qb7 Qc7 36.Qxc7 Bxc7 37.Bc4 Re8 38.Rd7 a4 39.Rxc7 axb3 40.Rf2 Rb8 41.Rb2 h5 42.Kg2 h4 43.Rc6 hxg3 44.hxg3 Rg8 45.Rxe6 Rxc4
1/2-1/2
but in the case danvm mentions, a4 is playable and means white is going to get the pawn back with nice development. my rybka gives almost a decisive plus to white after the 9th move, and the 4...b5 line is almost non existent (a few games against around 800 games in other moves) in my GM database.
But again, I can't say I really know what I'm talking about 🙂