The 1968 Moscow City Championship was a very strong tournament which included World Champion Tigran Petrosioan. He was, as is well known, a solid positional player and this was his second tournament in a row (the other was an international event in Bamberg, Germany) in which he did not lose a single game.
He was sometimes criticized for his strictly positional play, but that was simply a matter of preference; you do not get to be World Champion with out being very good at all phases of the game, including tactics.
Petrosian's opponent, Yakov Estrin (1923-1987) was an IM, theoretician, writer and World Correspondence Champion who held the Correspondence Grandmaster title.
Estrin was an authority on the Two Knights Defense. His game with Hans Berliner in which Berliner played the Two Knights and won is one of the most famous and important games in correspondence chess.
In OTB play, Chessmetrics estimates Estrin's highest ever rating to have been 2595 in 1974 and that placed him at number 90 in the world. At the time this game was played Chessmetrics estimates his rating to have been 2456 which was no where close to even the top 100.
As an opening theoretician, Estrin's poor play in the opening is quite surprising and Petrosian took advantage of it and crushed him.
Tigran Petrosian–Yakov Estrin1–0Moscow ChampionshipMoscow URS1968Stockfish 15
English Opening 1.c4 e5 2.g3 c6 3.g2 d6 4.c3 e6 Already a poor move
as this move has never worked well for black. Best is 4...g6 5.d3 g6 6.b4
d7 6...xb4 loses to 7.b3 a5 8.a3 c6 9.xb7 d4 10.b1
Black has no good continuation. For example... c8 11.e3 f5 12.b5
and there is no satisfactory way to meet Na7 7.b5 d8 8.f3 Black's poor
opening play has resulted in reaching a position where he has no really
satisfactory reply. g7 8...f6 9.a4 e7 10.0-0 g7 11.a3 0-0 White is
better. Perkins,A (2305)-Tarjan,J (2405) Graz 1972 8...h3 9.xh3 xh3 10.d4 g7 11.dxe5 e6 11...dxe5 12.a3 g4 13.0-0 Black's position is very
poor. Li,C (2680)-Makka,I (2154) Guben GER 2014 12.d5 with the advantage.
Li,C (2680)-Makka,I (2154) Guben GER 2014 8...h6 This probably black's
best reply. 9.0-0 g7 Here white should play... 10.b2 c5 11.bxc6 xc6 12.d2 with the better game. 9.g5 e4 Not good. Because white is better
developed the opening of the position is unfavorable for black. A developing
move like 9...Nf6 or 9....Bf5 was better. 10.b2 Naturally, Petrosian is
not going to fall for taking the e-Pawn. 10.gxe4 f5 wins the N. 10...exd3 11.xd3 a6 This is a serious tactical error. 11...e7 keeps
fighting. 12.xe6 fxe6 and white is clearly better, but at least black has
some hope of defending himself. 12.h4 Petrosian had a number reasonable
positional continuations available, but here, especially against Estrin's weak
opposition, he prefers to go for the throat. Black has a number of
difficulties: his K will not be safe on either wing and trouble is brewing on
the a1-h7 diagonal which he carelessly opened on mpve 9. axb5 13.cxb5 e7 14.d2 0-0 Castling into trouble, but there weren't any really good options. 14...d5 15.ce4 d4 15...dxe4 16.xd7+ wins material. 16.a4 d5 17.c5 d6 18.ge4 xe4 19.xe4 b6 20.a5 xb5 21.xd4 0-0 21...xd4 22.xd4
White is winning. 22.xg7 xg7 23.c3+ with a clear advantage. 15.h5 gxh5 Estrin appears to have a death wish. 15...h6 was
considerably better. 16.xe6 fxe6 17.a4 White has a clear positional
advantage. 16.xh5 16.xh7 is unsound because after xh7 17.xh5+ g8 18.e4 f6 White's attack is at a standstill and the advantage has shifted to
black. 16...f5 17.e4 White is clearly winning. g6 At first glance it
appears that black has managed to shore up his K-side, but white's next move
destroys the Ks defenses. 18.xh7 xh7 19.xh7+ h8 20.0-0-0 Bringing the
R into play. g8 21.h1 h6 22.d5 Bring his remaining pieces into play. f6 22...xb2+ 23.xb2+ f6 24.xh6 g7 25.g6 Black's position is
hopeless. 23.e4 xa2 23...df7 24.exf6 xb5 25.e7 c5+ 26.c2
mate is unavoidable. g5 27.xg5 xg5 27...e5 28.xh6+ xh6 29.xh6# 28.g6# 24.xh6 xh6 25.xh6 g7 26.h4 Black resigned. 26.h4 xh7 27.xf6+ xf6 28.xf6+ g7 29.xd8+ g8 30.xg8+ xg8 31.ec3 White wins
the ending. 1–0