zydeco: Good notes by both players on this game.
Petrosian's line is borrowed from Smyslov.
12....Qc7 is a bad inaccuracy - moving the queen for no good reason.
Najdorf feels that he's given white an advantage and begins to play very carefully. He calls 16.....b5 "a difficult move, which equalizes the game."
On move 31, Petrosian comments that "the game had become complicated in a rather lifeless way" - a strange statement which seems to mean that there were lots of intricate variations to calculate but nothing all that exciting.
Najdorf offered a draw on move 31. Petrosian declined it, and Najdorf, surprised, moved quickly and made the critical mistake with 31.....Rd4. 31....Nc3 would have led to complete equality.
45....h6 is a mistake. 45....h5 would have been better, reducing material further. Both players think that this endgame should be a draw, but Petrosian plays the last stage of the game perfectly.
On move 72, Najdorf had a decent chance with 72.....Nd7+ and the rook pawn will probably fall but leading to a theoretical draw. Petrosian comments: "But we must not forget that this was the last move before the time control, a moment which does not usually lend itself to the adoption of heroic decisions."
Najdorf sets a trap with 82....Kh7 and if 83.Rxf8 Rd5+ is stalemate.