Chess right of a deposed champion to a rematch, and the next champion, Armenian Tigran Petrosian, a player renowned for his defensive and positional skills, held the title for two cycles, 1963–1969. His successor, Boris Spassky from Russia (champion 1969–1972), won games in both positional and sharp tactical style. The next championship, the so-called Match of the Century, saw the first non-Soviet challenger since World War II, American Bobby Fischer, who defeated his Candidates opponents by unheard-of margins and clearly won the world championship match. In 1975, however, Fischer refused to defend his title against Soviet Anatoly Karpov when FIDE did
Bobby Fischer score would be nothing short of a lottery – the winner in that case could not claim to have won a convincing victory. Soviet grandmaster Lev Alburt felt that the decision to not concede to Fischer's demands rested on Karpov's "sober view of what he was capable of". Years later, in his 1992 match against Spassky, Fischer said that Karpov refused to play against him under Fischer's conditions. After the 1972 World Chess Championship, Fischer did not play a competitive game in public for nearly 20 years. In 1977 in Cambridge, Massachusetts, he played three games against the MIT Greenblatt