zydeco: Benko's notes on this game are very good and reveal his state of mind for his first game against Fischer. He knew that Fischer was a strong opponent but thought he could outfox him with a tricky opening.
Sure enough, the surprise move 7.Bg5!? (varying on Fuster's play against Fischer earlier in the tournament) provokes Fischer into unnecessarily giving up the centre. The right approach, says Benko, was 7....Nc6 8.d5 Nd4 9.Nxd4 exd4 10.Qxd4 h6 11.Bxf6 Bxf6 with compensation for the pawn.
Benko felt pretty good about things after 11....g5 and 13....d6 - he felt that Fischer was playing like a typical teenager in a positional game, psychologically incapable of solid, passive defense and creating weaknesses out of impatience.
With 14....Qa5, says Benko, he began "to appreciate the skills of [his] young opponent." The move is a positional sacrifice: if 15.Qxd6 Rfd8 16.Qa3 Qxa3 17.bxa3 and white's queenside is "a shambles."
But Benko was a step ahead and switched back to the kingside, showing that Fischer's queen was misplaced.
Benko was also impressed by 17....Qc7 and 23....Qf8, both of which showed good judgment.
After 26.Bxd8 Bd4+ turns the tables, but 26.Qg5! is a complete answer,
39.Kh2 was much simpler. Benko says that he was in terrible time trouble and missed black's reply to 39.Kf2.