Benko Gambit accepted

Hi, I thought I would write a short piece on the Benko Gambit with some example games.  It is a respected opening played at the highest level, all the top players have at times either played it as black or played against it as white, so it's worth knowing a bit about the opening.  It's an opening I have been experimenting with a bit in bullet games as it seems to be easy to play for black and gives white a few issues on the queenside.  For those of you unfamiliar with the gambit it starts 1.d4 Nf6, 2. c4 c5, 3. d5 b5 with the gambit fully accepted line continuing 4. cxb5 a6, 5. bxa6 (see postion below)

....so black has given up a pawn, what has he got in return?  Well on recapturing the a pawn (in the next few moves) he will have semi open files for both rooks and by fianchettoing his black bishop he can get long term pressure on white's queenside.  This often leads to recapturing the gambitted pawn and more.  Depending on white's sixth move black might stop white castling normally, for instance, 5....g6, 6. Nc3 Bxa6 7. e4 Bxf1 8. Kxf1 when black can develop normally with d6, Bg7, 0-0, Nd7 etc whilst white is manually castling his king via moves such as g3, Kg2 etc.

Obviously as with any gambit it is up to the gambiteer (if that is a word!) to prove his compensation for the pawn.  Black can get his heavy pieces on the a and b files, often his Knights do little dances via d7, b6, c4, sometimes the pawn move c4 frees up this square for a knight and he can hopefully exploit space in white's position behind white's e pawn.  From white's perspective he has to be careful not to be overrun on the queenside and wants to organise a timely e5 himself when black comes under pressure.  Here are a few example games:

[COMMENT DELETED]

[Event ""]
[Site "corr."]
[Date "1979.??.??"]
[Round "?"]
[White "Keino Heikki"]
[Black "Lehtinen Aimo"]
[Result "0-1"]
[ECO "A57"]
[WhiteElo "0"]
[BlackElo "0"]
[Annotator ""]
[Source ""]
[Remark ""]

1.d4 Nf6 2.c4 c5 3.d5 b5 4.b3 bxc4 5.bxc4 d6 6.Nc3 g6 7.Bb2 Bg7
8.Nf3 Nbd7 9.Nd2 Rb8 10.Qc2 Qa5 11.e3 Rxb2 12.Qxb2 Nxd5 13.cxd5
Bxc3 14.Qc1 Bxa1 15.Qxa1 O-O 16.Qb2 Nb6 17.e4 f5 18.Bd3 c4 19.Bc2
c3 20.Nb3 cxb2+ 21.Nxa5 fxe4 22.Bxe4 Bf5 23.Bxf5 Rxf5 0-1

[Event "It"]
[Site "Reggio Emilia (Italy)"]
[Date "1971.??.??"]
[Round "5"]
[White "Masera Umberto (ITA)"]
[Black "Benko Pal C (USA)"]
[Result "0-1"]
[ECO "A57"]
[WhiteElo "2094"]
[BlackElo "2525"]
[Annotator ""]
[Source ""]
[Remark "I(XII)"]

1.d4 Nf6 2.c4 c5 3.d5 b5 4.b3 bxc4 5.bxc4 d6 6.Nc3 g6 7.Bb2 Bg7
8.f3 Nbd7 9.e4 Rb8 10.Qc2 Qa5 11.Kf2 Nxe4+ 12.fxe4 Rxb2 13.Qxb2
Bxc3 14.Qc1 Nf6 15.Nf3 Nxe4+ 16.Ke3 Bxa1 17.Qxa1 Nf6 18.Bd3 O-O
19.h3 Ba6 20.Rb1 e5 21.dxe6 fxe6 22.Rb3 Qc7 23.Ra3 Bc8 24.Qb2
d5 25.Qe5 Ng4+ 0-1

How about ..4.Qc2 bc4 5.e4 etc.?

Thanks but no thanks. Or for instance 1.d4 Nf6 2. Nf3 c5 3. d5 g6 4. Nc3

Good point

i don't think it is sound to give up a pawn