Rybka preferred to play the capture hxg6+ for White on move 33 with this continuation possible: 33.hxg6+ Kxg6 34.gxh6 Qxh6 35.Rc2 Rh8 36.Rg2+ Kf7 37.Ng5+ Kf8 38.Qb3 Rg8 39.Qa4 Qh4 40.Qd7 Qh5

He lays himself open to counter-attack by first attacking with a huge queenside pawn attack-16 c4, then without resting starts a Kingside advance culminating in 32 h5.

Larsen chose to sacrifice a pawn on move 36. Hiarcs 10 preferred to protect the White c-pawn and suggested a variation involving the sacrifice of a pawn for black: 36.Rhc2 Kf8 37.Qa4 b5!? 38.cxb5 h4 39.Rxc8+ Nxc8 40.Qa3 Nd6 41.b6 h3 and White has compensation for the pawn.

On move 39,despite being 3 pawns down, Hiarcs 10 evaluates that Larsen has sufficient compensation for the pawns.

Hiarcs 10 gives Larsen an advantage after Spassky's 40th move of ...Qh6 .

Hi tamar I remember Steve Prefontaine, he was quite a runner. It is hard to believe he has been dead 31 years (sigh...where does the time fly?). I remember that Prefontaine was known for his extremely aggressive racing style, disliking the tactic of sitting and kicking, and always believing in giving a full effort.He is quoted as saying: ""To give anything less than your best is to sacrifice the Gift." I guess that is why he was so successful in his running career and why someone like Kasparov (despite his great natural talent for chess) has also been so successful. I remember Kasparov being quoted as saying (when he was World Champion,) "I study chess 8 hours a day everyday." Thanks for rekindling my fond memories of Steve Prefontaine :).

Spassky blundered by playing 58...Ra2?? however even after 58...Rf8 he would have lost after 59.Rg6+ Kh7 60.Kg4 Rb8 61.Kf4 Rb4 62.Rg4 Rb8 63.Kxe4 Ra8 64.f6! exf6 65.Kf5 Re8 66.e4 Ra8 67.e7 Kh6 68.e5 fxe5 69.Kxe5 Kh5 70.Rg1 Kh4 71.Ke6 Ra6+ 72.Kf7 Ra7 73.Kf8 Ra8+ 74.e8 (Q)

Spassky resigned on move 60 possibly due to this continuation: 60...Kg7 61.Rf7+ Kg8 62.Kg5 Rg2+ 63.Kf4 Rf2+ 64.Ke5 Ra2 65.Rxe7 Ra5+ 66.Kf6 Ra8 67.Rg7+ Kf8 68.e7+ Ke8 (the only move) 69.Rg8+ Kd7 70.Rxa8 with a checkmate after: 70...Kc6 71.e8(Q)+ Kc5 72.Qc8+ Kb4 73.Rb8+ Ka5 74.Qc3+ Ka6 75.Qa8 checkmate.

We've seen that Larsen's use of the Bird's was strategical and purposeful. 4. b4 ..., sets up the coming Q-side action. 7. ... c6, is necessary to forestall the advance b4-b5, and then 8. a4 ..., threatens a kind of Minority Attack.

11. d4 ..., blocks the Bb2, but it does much worse things to the black position. At first I did not like 11. ... Ne4, but since ... f5, is always in reserve I can see that the pawn e4 is not all that weak.

The position after 15. Qd1 ..., looks like something that Larsen has prepared in advance. The existence of the move allows the coming 16. c4 ....

The follow-up moves 17. b5 ..., and 19. bxc6 ..., present black with a crisis. Ordinary tactics like 19. ... Nxe3, followed by 20. ... Qxe5, do not work because of 20. cxb7! ..., with the Rb1 ready to support. Spassky's 19. ... b6, is ingenious in that it preserves his Q-side pawn structure, and after 21. ... Qxc6, he regains the material.

22. d5 ..., starts a whole new phase of the game. Somehow, Larsen has spied the e6 square and determines to put his Knight there no matter what the cost. With 24. Nd4 ..., he has it in hand but first makes a series of preparatory moves. When it comes on 31. Ne6 ..., black is reduced to nearly complete passivity. The sequence ending with 35. Nxg5+ ..., shows this clearly.

36. c5! ..., is a master-move. No matter what, white gains access to the checking square a4, and then access to all the white squares in the vicinity of the enemy King.

Black's passivity is now complete. In Zugzwang, he proceeds to wreck his position with pawn advances since his pieces cannot move. White waits until move 52 to play Qe6! which forces the Q-exchange. The threat 54. Nh7 mate, is the point which allows 54. Nxe4 ..., and 55. Nxc3.

But now it is Boris who cooperates with 55. ... Ne4?, which is surely a blunder. After the exchanges, white's pawns regain their mobility and in just three moves it is over -- the e-pawn is going to queen.

Does the presence of 55. ...Rd8, nullify Larsen's masterpiece? Only for chess-theorists. Larsen created the conditions that produced the blunder in the critical game, which in itself is chess of the highest order. Remember, Spassky had obtained 8 points in his last 10 games in this tournament; he was very very tough to beat at this moment.

What about

44. Rg7+ for Larsen

Would this be a bad move? It wins him either a queen for a rook and a knight, putting his king in "safety" or otherwise wins him a knight and a pawn, if black doesn't accept the queen lose by Rxe7, Qxe6, although it puts white's king in many many checks and rather a dangerous situation.

What do you guys think about 44. Rg7+ ?

The penultimate round, actually. In the final round Spassky managed to win against Quinones (Spassky vs O Quinones, 1964) and make up for this loss, sharing 1st place with Smyslov, Larsen and Tal.