In sports arena, you are my greatest rival! (6)

Karpov is a Russian chess grandmaster and former World Champion. He was the official world champion from 1975 to 1985 when he was defeated by Garry Kasparov. He played three matches against Kasparov for the title from 1986 to 1990, before becoming FIDE World Champion once again after Kasparov broke away from FIDE in 1993. He held the title until 1999, when he resigned his title in protest against FIDE's new world championship rules. For his decades-long standing among the world's elite, Karpov is considered one of the greatest players of all time.