shr0pshire: The English Attack Translated:
11. g4. If this position looks familiar, it is because it should! This is very similar to positions that arise out of the sicilian dragon. In fact pioneering English players took some of the theory from the Yugoslav attack in the sicilian dragon and applied it to the Najdorf.
Just like in the Yugoslav attack there will be a pawn race on both wings. White will fight on the kingside, and black will attack on the queenside.
Fischer vs C Munoz, 1960
Look at the similarities between this game and the Fischer game. You can learn a lot about the English Attack by studying the Yugolsav attack and visa versa.
14. ... Nc4. Black here would love to trade off his knight for white's dark sqaured bishop. Instead, white trades off his light squared bishop to decrease some of the pressure on white's queenside that the menacing knight brought.
21. Rxd5 This was the end of a quick liquidation of minor pieces. The semi-open B file and a black rook and queen aiming right at white's king made white uncomfortable and decided to trade off the positions.
Normally, queens, rooks, with same colored bishops would be a drawn endgame. However there are positional aspects that give the advantage to black at move 21.
Positional advantages for black on move 21.:
1. The semi-open B file. This provides a lot of potential for attacks on the white king, and with the bigger pieces on the board, this can be a very big liability.
2. Black's C pawn was successfully pushed to weaken black's king side even more.
3. Black's king is not only hiding behind his own pawns, but white's bigger pieces are blocked from directly attacking black's king at the moment because of his pawns. If white wants to stage a direct assualt on black's king he may have to push a few pawns first which will take some time.
These three things lead to a better position for black.