Muhammad Ali: Gave film his full backing

"The first time I met Ali I was like everyone else. You're meeting almost a biblical figure - you're meeting someone that legends are made of," said Smith.

He added that the boxer was quick to put the young actor at ease. "He said, 'man, you're almost pretty enough to play me.'"

Destined

Ali, who has never been known for his modesty, kept up the good-humoured teasing of Smith well into the filming of the movie.

The joke, according to the actor, eventually became a two-way process.

"He saw me in training and he told me that people were saying that I was almost pretty enough to play him and I said, 'well, that's funny, because those same people said I'm way too pretty to be playing you.'"

It's a relief to be finished - this film was really gruelling

Will Smith

Smith has come a long way since his Grammy-winning days as the latter half of DJ Jazzy Jeff and the Fresh Prince.

The sitcom, The Fresh Prince of Bel-Air, confirmed the young star as a consummate actor while blockbuster movies such as Independence Day, catapulted Smith into the so-called $20m club of Hollywood's leading men.

After initially turning down the role, Smith has said he now feels that he was destined to portray the world's most famous boxer.

"Some people are just born to do certain things," he said.

Smith: Physical, emotional and mental stretch

The film cost $110m (�76m) and was completed only after Smith and the director, Michael Mann, agreed to take pay cuts and personally take responsibility for any costs that ran over the budget.

"It's a relief to be finished - this film was really gruelling," said Smith.

However, he explained that much of the tension was associated with the complexity of the character he was playing - rather than the financial strains.

"I've been to my physical and emotional and mental and spiritual ends to create this interpretation so my hope is that people will get from the film what I got from the experience."

Family backing

Ali and his family have given the film their full backing - with the condition that it did not appear as a sanitised version of the boxer's life.

"Muhammad Ali is and has always been a man of the truth and that's what he said to me," said Smith.

"There were moments in the script - his interactions with his wives - I asked him about the authenticity of these moments 'Is there any one point that you want me to make,' and he said, 'just tell the truth.'"

I desire perfection - I desire being the best that I can possibly be

Will Smith

During his heyday in the 60s and 70s Ali served as a lightning rod in both the boxing arena and the political world when he refused to go to Vietnam.

"I believe that this film depicts Muhammad Ali as the the ultimate patriot," said Smith.

Ambition

"The freedom of speech that we have in this country is specifically designed in order that it be incumbent on Americans to stand up in the face of what someone might perceive as an injustice and say, 'no, stop, why are we in Vietnam?'"

It has been suggested that in the wake of the 11 September terrorist attacks, the film's attention to Ali's Islamic faith may not play well with US audiences.

"Muhammad Ali is a Muslim but Mohammed Ali is a man of God.

"Muhammad Ali is one of the few people who specifically stands out that says I am a Muslim that is welcome anywhere. Muhammad Ali can go anywhere," said Smith.

Smith, who has acknowledged an ambition to become America's first black president, added that Ali's achievements in the boxing ring reflect some of his own aspirations.

"I desire perfection. I desire being the best that I can possibly be. I don't want to take time to eat. I don't want to take time to sleep.

"I want to let the other guy be eating and sleeping while I'm working and while I'm trying to achieve my best earthly perfection."