Viktor Lvovich Korchnoi (Ви́ктор Льво́вич Корчно́й), born March 23, 1931, in Leningrad, USSR, is a professional Swiss chess player and currently the oldest active grandmaster on the world tournament circuit. Korchnoi is best known for playing three matches against Anatoly Karpov for the World Chess Championship. In 1974, he lost the Candidates final to Karpov, who went on to win the World championship by forfeit against Bobby Fischer). Wikipedia
The definitive Wikipedia entry for Viktor Korchnoi. Wikipedia is the biggest multilingual free-content encyclopedia on the Internet. en.wikipedia.org/wiki/Viktor_Korchnoi
