Blockaded Pawns Interfere with Rooks

The next position in the series on Petrosian's Exchange Sacrifice, again shows Petrosian sacrificing an exchange to escape from a difficult position. On the diagrammed position, he explained his reasoning for offering the sacrifice.

Petrosian: An experienced player could tell at once that White's position is rather difficult. Black's pieces are very active, and he has mobile e- and f-Pawns. If he advances his e-Pawn (e.g. after ...Rf6 and ...Raf8), White would be in great danger. Usually if one's opponent has hanging Pawns one should try to provoke the advance of one Pawn in order to blockade them by occupying the weak square in front of the rear Pawn (e4 here). But now the square e4 is beyond White's control because of the very favorable placement of Black's minor pieces.

Black continued 25...Ra6.

Petrosian: He could play 25...Rf6 followed by 26...Raf8. The text move is more inventive: Gligoric moves his Rook to f6 via the sixth rank and avoids any need of calculating the consequences of 26.d6.

Now the move 26.Bf3 took control of e4, but left d3 for Black's minor pieces. The control of e4 has tactical support.

Petrosian: White would seem to be making a mistake as now 26...e4 could follow with a gain of tempo. However, White's response would be 27.Qd4 when 27...Nd3 would be met by the same exchange sacrifice as in the game, but the Pawn e4 would hang. If 27...Qe7, then 28.Re2 with very sharp play.

26...Raf6

Petrosian: White's position seems completely hopeless. Black intends to play 27...e4, possibly preceded by ...b6. White seems to have no way of taking control of e4 because his Rooks are misplaced and cannot be moved to the e-file: 27.Re2 Bd3, or 27.Re1 Nd3, apparently with dark prospects for White. But nevertheless I played 27.Re1!, a purely positional exchange sacrifice. Again White does not wait to make a decision. He makes it because he has foreseen eventual consequences and realizes what could happen.

Varna Olympiad 1962
Gligoric, Svetozar

Petrosian, Tigran
(After 25.Kg1-h1)
[FEN "r4rk1/1pp5/6bp/p1nPp1q1/2P2p2/2N5/PP1QBRPP/5R1K b - - 0 25"]

27.Re1 How many players would walk voluntarily into the Knight fork? 27...Nd3 28.Rfe2 Nxe1 29.Qxe1

Petrosian: The Pawn e5 hangs. If Black gives it up White would have a Pawn as compensation for the exchange.

29...Re8 30.c5

Petrosian: Yes, Black has the exchange extra, but if you have some time to consider the position attentively, and try some lines, you should feel that the material plus means nothing. Gligoric failed to find something better than 30...Rff8 31.Ne4 and he offered a draw.

1/2-1/2. To play through the complete game see...

Tigran Vartanovich Petrosian vs Svetozar Gligoric, Olympiad 1962
http://www.chessgames.com/perl/chessgame?gid=1106589

...on Chessgames.com.