May 25th 1965 Muhammad Ali vs Sonny Liston, Lewiston, Maine, KO 1

Because of the unexpected ending of the first bout, boxing authorities ordered a rematch, this time with Liston as challenger. The ending of the second fight remains one of the most controversial in boxing history. Midway through the first round, Liston fell to the canvas, in what many have argued was not a legitimate knockdown.