It is very difficult to answer to that question; That would change history in general or history of boxing? I've heard a lot of good calling there; Tyson-Duglas, Ali-Liston, Ali-Frasier III, Personally, I think that I would go with Foreman-Ali with rumble in the Jungle;

BEcause it is one of the most important fights that did catapult Ali's career and because this fight was the one that did throw forward the career of Don King in the skies.. and we all know how that old fat bastard just by himself changed the history of boxing and I can't imagine how it would be now if it would have taken all another direction.