I might of said When We Were Kings from 1996, but that's a documentary, so I'd also think Ali, the Will Smith movie, I was also going to post that as per Destination's suggestion, haven't seen it but it might feature a montage of him, though Ali was set 20 years earlier than 1996.
Though this might also not feature Ali in it prominently at all though, could just a character TV watching red herring in a completely different movie. Something with sports and betting maybe.