This instructional battle waged between two of the elite stars of chess, T. Petrosian (white) and Bent Larsen, the Dane, (black), provides a fine example of imbalance and fight between two distinct styles of chessplay.
1.c4 Nf6 2.Nc3 g6 3.g3 Bg7 4.Bg2 0-0 5.d4 Another approach for white here is 5.d3 keeping it in a type of English Opening. Now it appears to be a King’s Indian Defense.
5…d6 6.e3 c6 7.Nge2 a5 8.b3 Na6 9.0-0 e5 White pawn structure while solid is rather timid (e3) and black launches an immediate hit on the center.
10.Bb2 Re8 11.a3 Threatening b4. Do you see why this is possible?
11…Rb8 Removing the Rook from the a-file stops b4 and supports a possible b5 counteraction on the Q-wing.
12.h3 Typical Petrosian prophylactic defense keeping g4 taboo for any black piece taking up residence.
12…h5! Gaining square count and prevents a possible g4 opening the g3 sq for N occupation.
13.Qc2 Connecting the two Rooks and pressuring the w/sq diagonal.
13…Be6 14.Kh2 Qc7 15.Rac1 b5. Placing a Rook opposite the enemy Queen is almost always a good tactic. Black forces and pawn structure are dynamic and the imbalance reached should produce a tense struggle for the advantage. Here the styles clash between Petrosian and Larsen in the nature of how they perceive position goals.
16.cxb5 cxb5 17.Qd1 Qe7 18.Nb1 Apparently following a long standing concept of Petrosian to reposition forces and mark time with the intention of simply improving his forces for the next phase. However, this is slow and he overlooks in the short term what black intends.
18…Bd7 19.Nd2 e4! Black shuts the door on central tension and most importantly makes white’s Bb2 bad and worse than that seen in the French Defense bad bishop scenerio. Now with inroads into the white territory he secures domination over the light squares and increases his spatial edge.
20.Nf4 d5 21.Qe2 Qd6 This sneaky little move has a sting to it. Can you visualize its purpose?
22.Rc2 Rec8 23.Rfc1 Rxc2 24.Rxc2 h4! Going full force into the guts of the enemy camp, an excellent example of my theory of square count strategy. Of course gxh5 Nh5 would be suicide and now you see the purpose behind Qd6.
25.Nf1 hxg3+ 26.fxg3 Creating 3-pawn islands thus weakening the white pawn structure.
26…b4 With the aim of curtailing Q-side activity by white.
27.a4 Rc8 28.Rxc8+ Bxc8 29.h4 Nc7 30.Bh3 Bxh3 31.Nxh3
What a horrible position Petrosian finds himself. The Bb2 is bad with little future; the N pair have little to do and the Q is virtually cut off from any aggressive opportunities. Black with his spatial edge can now maneuver his units to more aggressive posts without interference from white threats who can only sit and wait for the pending disaster to strike.
31…Bf8 32.Kg2 Qc6 33.Qd1 Bd6 34.Nf2 Ne6 35.Bc1 Ng7 36.Bd2 Nf5 Hitting d4,e3,g3,h4.
37.Kh3 Qc8 38.Kg2 Kg7 39.Nh1 Nh6 40.Be1 Qa6 41.Nf2 Nf5 42.Qd2 Bb8 43.Nd1 Ng4 44.Kg1 f6 45.Kg2 g5 46.Nf2 Ngh6 Exchanges would only aid the white defense.
47.hxg5 fxg5 48.Nd1 Kg6 49.Nh2 Kg5 50.Qc2 Bd6 51.Nf1 Kh5 52.Nh2 Kg5 53.Nf1 Kh5 54.Nh2 Kg5 White is in zugswang where each move only worsens his position as black continues to prepare the final breakthrough.
55.Nf1 Nh5 56.Bf2 Nf6 57.Be1 Nh5 58.Bf2 Qa8 59.Be1 Qh8 60.Qc6 Bxg3 61.Bxg3 Nhxg3 White Resigns. 0-1.
Lessons to learn: Beware of simply playing the opening with a positional sense of solidity. Here the desire to keep the diagonal open for the Bg2 prompted 6.e3 and, while solid, gave black an immediate opportunity to strike at the center and increase development leading to harmonious piece cooperation. Perhaps white might have tried dxe5 no matter what just to provide some freedom of movement for the Bb2 and try to create some open lines. Still, black was probably better prepared to handle the resulting position.