If Will Smith is looking a bit diesel these days (as evidenced by his bulked-up, 217-pound frame), it's because for the past six months he's been preparing for his role as titular boxing great Muhammad Ali in director Michael Mann's upcoming Ali biopic. Listening to Smith recount his intensive training regimen, the question arises: Did the wannabe contender suffer any injuries in the ring?

"Oh, only injuries!" Smith tells TV Guide Online with a hearty laugh. "But it's all part of being a boxer. We've created a real training atmosphere."

Adding realism to his prep work were visits by Ali himself; The Greatest's onetime trainer, Angelo Dundee; and Sugar Ray Leonard. "Sugar Ray came into the gym, and we sparred a little bit," Smith shares, adding that the onetime Olympic champion still has the right moves. "You can't hit him! He's never where you throw your fist. He's so fast."

As the actor masters his jabs and hooks, he has gained an insight into a fighter's sense of confidence. "Within three weeks of training, you can whoop anybody's ass," he asserts, then illustrates one of the basics. "Anybody that is ever going to throw a punch at you in the street is going to throw a looping right hand, period. That's the only punch that's coming. Except for that one left-handed guy!"

If Ali, which resumed production after getting sucker-punched with a brief budget snafu, promises a physical Smith, this Friday's The Legend of Bagger Vance — in which he has the title role, as an enigmatic golf caddie — offers a look at his rarely tapped more cerebral side.

"People pay a lot of money for the 'Will Smith' thing," he notes, explaining that director Robert Redford was just the person to take him into new territory. "I felt comfortable talking with him because he has created a persona, yet navigated those treacherous waters to become respected as an actor."

While Smith's touching portrayal of Vance ultimately emerges as soft-spoken and mystical, he admits that a familiar devil occasionally appeared on his shoulder. "That dude inside of me was like, 'This is our chance, man! Say something funny and steal the scene!'" Smith, though, brushed off such temptations. "The ultimate compliment came when the people from DreamWorks told my manager, 'Your client has a film that you're going to be really proud of, but he didn't give us one moment to put in the trailer.' That means I was successful in being able to 'turn it off.'"