The actor who almost wasn't

'I can't imagine anyone saying this is their favourite thing to do,' says Joaquin Phoenix, shifting in his seat, drawing on a cigarette and, most notably, watching his every word. Sporting a loose fitting shirt and khakis, he does his best impression of a man looking relaxed on the opening night of a $70 million movie in the middle of an unrelenting New York heatwave.

It's not a bad show, all things considered. And in a way, it's not all that different from the performances he puts up on screen - at once open and guarded, vulnerable yet menacing. A dark Tobey Maguire, if you will. 'The part I love most about this job is the acting itself,' he says, searching about for an ashtray in his hotel suite. 'Obvious, I know. But there are those brief moments when you actually tap into something. And for about 30 seconds, you almost feel invincible.'

Phoenix is not a new face in Hollywood. But it did take 18 years in front of the cameras to finally make a name for himself. The film that did it was Gladiator, for which the 27-year-old actor, starring opposite Russell Crowe as the power-mad Emperor Commodus, received his first Oscar nomination. 'Everyone asks about the impact of Gladiator on my career, but the truth is, I don't really know,' he shrugs. 'The quantity and the quality of the scripts changed for the better, but it hasn't changed my life.'

Indeed, Phoenix wasn't even the first choice for M. Night Shyamalan's latest thriller, Signs. 'On every movie I've ever made, there were 20 other people who were meant to play the part,' he readily admits. But following the strong performance of Signs in the US - earning $60 million on its opening weekend and en route to becoming one of the year's biggest hits - his stature within the industry is likely to expand.

As Merrill Hess, Phoenix again plays second fiddle, this time opposite Mel Gibson. A trusting younger brother and failed former athlete whose quiet life is shattered by the appearance of crop circles in the family's Pennsylvania cornfields. Like The Sixth Sense and Unbreakable, it's a familiar Shyamalan milieu in which audiences are left on the edges of their seats until the film's final frames. But so, too, is there a welcome dose of humour to underscore the absurdity, thanks largely to the presence of Phoenix - in one scene, he goes so far as to join the Hess family children (Rory Culkin and Abigail Breslin) in donning aluminum foil hats to prevent suspected alien invaders from reading their minds.

Not surprisingly, Phoenix admits he almost didn't take the job at all. 'They came to me about two days before we had to start which seemed like a recipe for disaster. I didn't think I could pull it off,' he says. 'The thing is, you don't really want to bomb in a huge movie M. Night Shyamalan is directing. But when we met, Night gave me the script and said, "Just come down to Philadelphia and shoot it with me." His utter confidence is what won me over in the end. And without that I wouldn't have jumped.'

Phoenix's own story is well known if decidedly surreal. Born in Puerto Rico, the middle child in a brood of five, he moved with his hippie family across Central and South America, eventually settling in California after his parents' doomed flirtation with a religious sect. Following in the footsteps of his older brother, River, Joaquin (who changed his name to Leaf for a spell to match his siblings - Rain, Liberty and Summer) turned to acting. He made his television debut at the age of eight, his film debut four years later in the comedy, Space Camp (1986), and his first big screen hit with Parenthood in 1989.

Nevertheless, he was already having doubts about his career. 'I was at that age where you start thinking, what am I doing with my life,' says Phoenix, who simply abandoned acting altogether. Following his brother River's death from a drug overdose outside the Viper Room in 1993 - it was Joaquin who put in the now infamous call to emergency services - it seemed unlikely that Joaquin would ever return to acting. 'When I stepped away from acting I knew I was missing something,' he says, cautiously. 'Eventually I came to New York and started auditioning for jobs again. But I didn't want to do any of them,' he says with a nervous burst of laughter. 'I'm such an idiot.'

Phoenix returned to the screen for Gus Van Sant in To Die For with Nicole Kidman in 1995. It remains, arguably, his best work. And like Signs, it turns out, one that almost didn't happen either. 'When I first heard about it, I thought, what a terrible idea - a teacher seduces this kid and he kills her husband? That's awful. About a month later my agent calls back and says, "Read the script!" And I was like, "Joaq - what are you doing? You've ruined it." I drove up to New York, went in for an audition with Gus, and that was it.'

Phoenix has been steadily building his career since, his name infiltrating the tabloids with a two-year romance with Inventing The Abbots co-star Liv Tyler, and, more importantly, winning industry attention with assured performances in Oliver Stone's U Turn, Return To Paradise, Gladiator, and most recently, Quills. 'He just shows up and lets it rip,' says Mel Gibson of Phoenix's work in Signs. 'what he does, it's natural and instinctive - far less mannered than anything I do.' Shyamalan puts it more succinctly. 'If he wanted to, he could be the biggest actor in the world.'