An old teacher of mine once said that if you were to dramatize a famous person's life (i.e. make a "biopic"), it would be most effective to stage your story on one day - preferably a critical day of that person's life - rather than try to recount the entire cradle-to-grave scope of their existence.

That's a bit extreme, but I agree to some extent. So, too, does Michael Mann, it seems, as instead of covering the whole first 60 years of Muhammad Ali's time on earth, he focuses on the former boxer's 10 most dramatic: from his victory over Sonny Liston in 1964, winning the heavyweight championship, through his conversion to Islam, his friendship with Malcolm X, his notorious refusal of the Vietnam draft, his first two wives, and finally wrapping up in 1974 when, at 32, he reclaimed the heavyweight title against George Foreman in their legendary "Rumble in the Jungle" fight in Kinshasha, Zaire.

The ten-year time frame is a wise choice: Ali's subsequent bouts with the forgettable Leon Spinks, and eventual slide into the heartbreak of Parkinson's disease, are things we really don't need to relive. Still and all, Mann seems less interested in telling a story (after all, his hero is pretty much in the same place at the end of the film as he is in the beginning) or even painting a portrait of the man's soul than he is in showcasing the former Cassius Clay as a symbol for a turbulent time in American history, from the new ideologies dawning in the mid-'60s to the me-first mid-'70s. Because of his race, because of his fame, because of his integrity, because of his attitude, Ali is seen by Mann as the embodiment of all the good and bad that happened in that era.

An ambitious goal. Too bad Ali doesn't live up to these ambitions, not to mention the ambitions of the man himself. Part of this might lie in Mann's last film, the excellent The Insider. Mann finally settled on a mature visual style with that film, and he uses it again here, note for note, in Ali. The tight focus, the off-center framing, the bold cuts - it's all there and it's all good. It's just that was all there in The Insider too, but there it served a tighter story that had more immediacy.

As for Will Smith in the title role, he more represents Muhammad Ali than impersonates him. His much-noted muscle gain is crucial to the part. But although he fast-talks it like the champ, he doesn't try to ape Ali's famous rasp or his bug-eyed glower. Which is an interesting choice, given that his costar John Voight is rendered completely unrecognizable under pounds of make-up as sportscaster Howard Cosell. (Voight's terrific, by the way.)

Though we may not learn much about Muhammad Ali that we hadn't already guessed - that he loved the limelight, that he was a ladies' man, that he was a great boxer - watching the film is an undeniably visceral and thought-provoking experience. And if nothing else, you'll get a real sense for how physically exhausting a few rounds in the ring can be, even for "The Greatest".