Korch was within one game in a long match of winning the world championship two different times in his forties. The champ was a young twentysomething Karpov.

Then he went on to be the best fiftysomething chess player ever to play the game in his fifties. And the best sixtysomething in his sixties. And the best seventy-something in his seventies.

He had a stroke right around age eighty but managed to slip in at least one win against American grandmaster and world championship candidate Fabiano Caruana in 2011 after he turned eighty, so he was the best ever of that decade as well.

Chess players usually peak a bit before thirty. Korchnoi defected after forty. As a dissident under the Soviet system, Korchnoi didn't have the chance to prove himself in international competition in his twenties or thirties, but he may have been the best in the world for a long time before Karpov or Fischer reached the championship.