Ali greatest victories were against Liston and Foreman.
Both men were undefeated, had never been knocked down, and were feared for their close range power.
Ali v Liston:
When the young Clay challenged Liston for the title, nobody gave him a chance.
Ali beat him and took the title.
In the re-match, Ali put Liston down for the first time in his career.
See footage here:
http://whitetigermartialarts.blogspot.com/2011/01/ali-v-liston.html
Ali v Foreman:
In the case of Foreman, he had won 2nd round KOs against both Frazier and Norton.
Both Frazier and Norton had previously gone the distance with Ali and beaten him.
Nobody, on paper, gave Ali a chance against Big George.
Ali completely outboxed Foreman and took his title at The Rumble In The Jungle.
See Ali-Foreman footage here:
http://whitetigermartialarts.blogspot.com/2011/01/ali-ko-foreman-rumble-in-jungle.html
Ali v Tyson:
A match we never got to see but would all probably have liked to.
Having seen the way Ali took care of Liston and Foreman how do you think he would have handled Tyson?