In What to Do with Passive Rooks?, I left Petrosian's notes at the diagrammed position, where the ninth World Champion commented, 'A Rook, by no means forced, goes to a square attacked by a minor piece.' See the previous post for the link to the PGN and Java game viewer on Chessgames.com.
The game continued 32.Bxf4, which Petrosian judged inferior.
If Tal realized all the consequences he would be satisfied with a gain of a Pawn: 32.Rxf4 exf4 33.Bxf4 Bxf4 34.Qxf4 Qe7. Black would be a Pawn down, but the position quite unclear. His Knight would be able to go to e5, the Pawn d5 would be stopped. I thought this position would be better than a cramped position with a material balance.
Now after 32...exf4, White tried 33.Nd2, 'The Knight is the only White piece that can fight for e5, so Tal wants to move it to f3. Perhaps 33.Nc1 & 34.Nd3, with the same idea, would be better.'
[FEN "3q1rk1/3n1ppp/p2b4/P1pPp2P/1pP1PrQ1/1N2B3/1P4P1/R4RK1 w - - 0 32"]
Note how Black's moves suggest themselves, but White has decisions to make. 33...Ne5. Black committed to the sacrifice because it gave optimum play for the remaining minor pieces. 34.Qxf4.
White is not forced to capture this Pawn. He could play e.g. 34.Qe2. Then Black would have a number of possibilities: 34...g5 & 34...Qh4. It is hard to say that White's extra exchange would be tangible. Tal realized that events were taking a bad turn for him, so he tried to complicate matters.
34...Nxc4 35.e5 Nxe5. Petrosian: 'By means of counter sacrifices White has opened files for his Rooks. However Black has plenty of counter chances.' 36.Ne4 h6 37.Rae1 Bb8 38.Rd1. 'Those who want to to practise calculating are advised to study this game starting from the 38th or 39th move. There are a lot of interesting variations.' 38...c4 39.d6.
White is already faced with great difficulties: the threat is 39...Ba7+ followed by 40...Nd3 with attack against his King. Moreover, when the Knight comes to d3, the White Rook is cut off and the Pawn d5 is in danger. Tal seeks defending resources.
39...Nd3 40.Qg4 Ba7+ 41.Kh1 f5. The sealed move; if 42.Rxf5, then 42...Rxf5 43.Qxf5 Qh4+ 44.Qh3 Qxe4. 42.Nf6+. Now after a number of exchanges, Petrosian noted, 'Black has good winning chances, but I failed to exploit them, and the game ended in a draw.'