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 living in Moscow. FBI files do not identify Nemenyi as Fischer's father, but note that Hans-Gerhardt Fischer never entered the United States, while recording that Nemenyi took a keen interest in Fischer's upbringing. Not only were Regina and Nemenyi reported to have had an affair in 1942, but Nemenyi made monthly child support payments to Regina and paid for Bobby's schooling until his own death in 1952. In addition, Nicholas and Benson found letters by Nemenyi's first son, Peter, identifying Bobby Fischer as his brother. In March 1949, 6-year-old Bobby and his sister Joan learned how to play chess using