|A nightmare come true|
Back in 1962 at the Candidates Tournament in Curacao the three top finishers (Petrosian, Geller and Keres) drew all twelve of their games against each other in an average of only 19 moves. Soon after the tournament Bobby Fischer alleged that the Soviets had colluded to prevent any non-Soviet – specifically him – from winning. His allegations were twofold. First, that Petrosian, Geller and Keres had prearranged to draw all their games. Yuri Averbakh, who was head of the Soviet team, confirmed Fischer's claim in a 2002 interview. Reuben Fine had made the same accusation against Soviet players back in the 1940s.
Fischer also claimed that Korchnoi was forced to throw games, but after he defected from the USSR in 1976, Dominic Lawson called the allegation "preposterous", noting that the main beneficiary of Korchnoi's losses was Petrosian, whom Korchnoi detested. Korchnoi also wrote that he was surprised by the short draws.
There were also allegations that, in the ultimately decisive Benko-Keres game in the penultimate round (which Benko won), Petrosian and Geller (who were good friends) conspired against Keres by offering to help Benko. Benko has written that Petrosian and Geller offered to help analyze the adjourned position, but that he refused the offer.
As a result of all the allegations FIDE changed the format of the Candidates' Tournaments and in 1966 a series of elimination matches was instituted. Ex-Champion Botvinnik and Paul Keres (2nd place in the 1962 Candidates) were seeded into the matches, but Botvinnik declined and his place was taken by Efim Geller, who finished 3rd in the 1962 Candidates.
Tal made his sacrifice based on general considerations, but it put Larsen in the position of having to find some tricky tactics if he was going to hold the game. It also demonstrates the necessity of finding the most efficient way to win after obtaining a superior position.
Tal was known as a great attacking player, but he was not a one sided genius; he could play positional chess and endings with the best of them, but his preference was tactical melees. His play was characterized by the following:
* Keep his opponent's King in the center if possible
* Breakthrough in the center
* Get the initiative which enabled him to increase the assault ratio
* Open files and diagonals
* Secure outposts for his pieces
* Eliminate defenders of the opponent's King
* Weaken the opponent's King's position