Ali

A potent portrayal of Ali, a fighter in and out of the ring

Limiting himself to the decade between 1964 and 1974, Michael Mann's film – given its royal premiere last night – traces the rise and fall, and rise again of Muhammad Ali.

It is hardly a new subject – it would be hard to find anyone the world over who had not at least heard of the boxer with the lightning feet and even quicker wit – yet in Ali, Mann takes a well-known text and presents it in a form that takes us deeper into an understanding of both Ali the man and Ali the icon.

Ali was always perfect material for Mann: the director of Thief, Manhunter, Heat and The Insider is thoroughly engaged with the question of what it is that makes a man ... and what threatens to unmake him. Mann's heroes are necessarily flawed, made heroic by their constant search for self-improvement. What compels these men is the need to be the best they can possibly be.

For Ali, Mann suggests, that struggle is only played out in part in the ring. It is also personal – his faith in Islam always at odds with his predilection for beautiful women. And public – both celebrated by a black community at war with racism in the US, and vilified by patriots for refusing the Vietnam draft.

His absolute belief in his right to be free in thought and deed was his underpinning: "I'm gonna be the champ the way I want to be, not the way you tell me I should," says Ali (Will Smith) to the reporters who seek to pigeonhole him.

Smith is outstanding. There is not a shred of mimicry in his performance, rather he carries himself with such conviction he appears to inhabit Ali. He follows a noble line of actors – Robert De Niro, Daniel Day Lewis – who took the job so seriously they could have entered the ring for real, but Smith is equally impressive when called upon to explore the private, contemplative Ali.

These reflective moments are where Mann excels. Sure, the fight scenes are conducted with visceral panache, but Mann is a master at letting a movie and a character breathe; he frames faces better than any film-maker at work today.

Mann places Ali firmly in the civil rights politics of the time, never shying from the uncomfortable stuff: Don King's relationship with Zaire's President Mobutu for the "Rumble in the Jungle"; Ali's own complicated relationship with the Nation of Islam (who gave him his name).

Mann hasn't simply rehashed the myth of Ali, he has deconstructed it, pieced back together the person at the heart of it, and created a more human – and thus more potent – image than previously existed. In the process he proves himself one of the very few auteurs at work in cinema today.