Genuine hate between fighters adds extra spice to a Boxing match. There was no bigger rivalry other than Muhummad Ali and Joe Frazier,.
Ali was banned from Boxing for refusing to be inducted into the Army in 1967 and therefore was stripped of his title as World Champion. After 3 years he was finally given his Boxing Licence back but Joe Frazier was now the Champion.
They fought 3 times with Ali winning the decider in 1975 in what is acknowledged by most as one of if not the best Heavyweight Title Bout there has ever been.