Get this straight from the start, Dwayne Johnson is not The Rock. The 35-year-old California native, a striking broadbeam giant of Samoan descent, has long since abandoned his wrestling persona. He is an actor now, and as if to prove the point he comprehensively savages his Rock-ish incarnation in the opening act of his new comedy The Game Plan.

Here, as the egotistical American Football superstar who's suddenly landed with an eight-year-old daughter from a past fling, Johnson pokes and prods everything that once made him an international icon of wrestling. Thus his name is the King, he has corny catchphrases, standard poses, corporate endorsements, a millionaire man-pad and a glib self-awareness that hides his crushing loneliness.

“There was a lot of winking to the audience going on,” says Johnson, who made his screen debut in The Mummy Returns (2001) and hasn't looked back since. “There's a lot of similarities between the King and The Rock, and with what I used to do with The Rock.”

He adds that despite the stream of movie roles, the respectable critical notices (he was widely praised for his deft comic turn as a gay bodyguard in Be Cool), and the upcoming blockbusters (he has three comedies and an action movie on the way), people still want to know when he'll be returning to the ring.

“I probably wouldn't get asked that question if I had made a bigger splash about my retirement,” he explains. “But I retired quietly five years ago. I didn't want it to be a grand exit, I just wanted to walk away, so I thanked everybody that I needed to thank, and did just that.”

Johnson's decision to quit wrestling was spontaneous, and compounded by his experiences on the Moroccan set of The Mummy Returns. He is from a family of professional wrestlers - his father and maternal grandfather were both hard-grafting grapplers - but he says that acting was instantly addictive. “I had only one line, and it wasn't even in English, but I knew then that I loved it,” he says. “But I also knew that if I had any future in the movie business I had to dedicate myself completely to it.”

Johnson speaks a lot about dedication, and goals, and focus. It's sports terminology, yes, gleaned from his years on a football scholarship at the University of Miami (he has a degree in criminology). But it's also the rhetoric of somebody who has turned his life around and is propelling himself forward by sheer willpower. He is open about his past in a way that's unusual for high-profile Hollywood-ites, but also suggests a supreme sense of confidence about his own future.

His childhood was tough, based in Hawaii but often travelling with his dad, “Soulman” Rocky Johnson. “I had to struggle constantly to stay on the right path and do the right thing,” he says. “I got into a lot of trouble, and by the time I was 15 I had been arrested multiple times.”

He explains, non-ironically, like the inspirational star of his own sports movie, that athletics saved him, and that a football coach at his last high school, in Pennsylvania, helped him to shift his focus on to the field, where he became a 6ft 5in, 16-stone mean machine who received scholarship offers from colleges around the country. But a back injury knocked him out of serious contention for a long-term football career, and he was forced into the family business. He slummed it at first on the low-rent carnival circuit, as Rocky Maivia, often wrestling for as little as £20 a night, before finding fame in the World Wrestling Federation as the Rock.

He says that right now he is where he wants to be, jumping between genres, clowning in comedies and excelling in action movies, such as the forthcoming Race to Witch Mountain. His private life is exclusively defined by his seven-year-old daughter Simone (he separated last June from his wife of ten years, Dany Garcia).

And still, he adds, there are more goals. Such as? To do better work, to hone his performances (he works with his longtime acting coach Larry Moss), to develop closer ties with the Hollywood studios and even, yes, to win an Oscar. “I had a chance to present an Oscar on Sunday and I was asked if I'd like to win one myself. And sure, of course, it's every actor's dream,” he says, with initially guarded enthusiasm. In fact, he adds, momentarily overtaken by the excitement of it all, “winning an Oscar is a goal of mine”.

To judge from his track record, if the Oscar win is a goal, then it's already in the bag. Just make sure they put the name Johnson on the trophy, and not Rock.

The Game Plan is released on March 7

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