IT was one of those moments that sound too scripted to be true. One of those moments that are too Hollywood. One of those classic moments, when an older actor crosses the generational divide, and in a poignant soliloquy, shares hard-won wisdom with the rookie. The rookie was Matt Damon, near-unknown 26-year-old lead in Francis Ford Coppola's adaptation of John Grisham's The Rainmaker; the grizzled vet was Mickey Rourke, cast as a seedy, compromised mentor to Damon's eager-beaver, idealistic attorney.

Rourke was reuniting with Coppola for the first time since 1983's Rumble Fish. Back then, 27-year-old Rourke was dripping with pomaded promise, another of the Coppola discoveries - Cage, Dillon, et al - tipped to stand in the cool continuum of Brando, De Niro and Pacino. That was before a potent mix of boozing, plastic surgery and pugilistic delusions turned him into a human punch line.

It was the first day of shooting on the set at Knoxville, Tennessee and Damon was nervous about doing a scene with Rourke, one of his heroes. The grizzled vet appeared at the rookie's side: 'You have a big opportunity, kid - I had that opportunity and I blew it. I fucked up and I'm hoping for another chance.' His voice was rising, and he seized Damon by the shoulders: 'Don't piss it away! You be polite to everyone you meet. It's "Yes sir, no sir." Focus on the work - don't waste your energy acting out. It gets you nowhere.'

More than a year later, Damon looks back. 'The business is rife with temptations. To be reminded of that, especially by your idols, is important; even someone who's not necessarily evil might take advantage of things offered.'

The prodigal son cruises the backstreets of his home town, Cambridge, Massachusetts. 'I can't believe they let them develop this land,' he says, shaking his head. It's his first week-long visit home since Good Will Hunting razed his old life and rocketed him and buddy Ben Affleck into rarefied social climes and unfamiliar tax brackets. 'The rents are gonna go right up and everyone is gonna get pushed out. It's unrecognisable. They've made it just like every other place in the country!'

A handpainted sign droops over one desolate storefront: 'You can't evict the spirit'. If this were a movie, you'd want to slap the director. But this is the very cinematic real life of Matt Damon - Harvard dropout, Oscar winner, and current consort of Winona Ryder. He is in work shirt, loose-fitting jeans, and black work boots. He carries himself like a local jock. There's barely time for one last look at the pizza joints where he and Affleck hung out as drama-class accomplices at the local high school. Indeed, there's little time for anything that's not. . . well. . . scripted.

Damon wishes he could stick around and play with Jackson, the baby boy of his older brother, Ky1e, a sculptor, but he's got to pack tonight for a six-month shoot overseas. He turns into a tree-lined street, stopping in front of a two-storey house. His parents divorced when he was two, and since the age of 10, his mother raised him and his brother in this quasi-communal abode they shared with six other families. A former neighbour approaches. 'My Mom?' Damon says breezily. 'She's doing great. Yeah, Dad too. . .'

Such was the media saturation over Affleck and Damon after Good Will Hunting (which they also wrote) that a certain amount of suspicion and contempt surrounds their story. Damon, like Affleck, wonders if he has 'whored out my personal life for professional gain'. And there is no harsher critic of his sudden fame than his mother, child-development professor Nancy Carlsson-Paige. She told the Washington Post of her reaction to one glossy magazine profile of her son: 'My beautiful boy. . . is being used to sell products. He is just a cog in the capitalist system.'

But that's a rare note of discord in Damon's family: unlike the lone-wolf genius Will Hunting, Damon has always been nurtured by his mother. And as the product of a 'progressive, leftist' household, he places as little value as his mother does on his exulted position in the Hollywood food chain. He knows he's been dealt a lucky hand.

But the main reason for his diffidence isn't the random nature of his fame. It's that he was promised all this before. Twice. School Ties (1992) was supposed to lift him into the major leagues, and in 1993 the anticipated success of Geronimo: An American Legend led him to abandon his English studies at Harvard a year short of graduation. (He had his mother's support.) Despite assured performances, neither film caught on. 'You get realistic,' he says. 'I wasn't looking to become an overpaid sensation.'

Expectations, however, can only be lowered so far. Damon's bottomed out four years ago in the tiny Texas town of Alpine, where he was shooting the TV movie The Good Old Boys. Sure, it was great to be acting opposite Sam Shepard with Tommy Lee Jones directing, but the 120-degree heat and three-hour drive to the airport were a little too suggestive of professional purgatory. 'At 19 I did a TV movie for $25,000,' he says. 'Five years later, after two feature films, I was getting $20,000 for another TV movie. Talk about a lesson in humility - somebody was obviously trying to tell me something.'

So, determined to escape, he hunkered down each night in his Comfort Inn room, emerging only to fax Affleck pages of Good Will Hunting, the script they hoped would raise them up from a life of obscurity. At Damon's side was girlfriend Skylar Satenstein, a Harvard student, who teasingly suggested he model Will Hunting's love interest on herself. He did just that. In further script-within-a-script twists, Damon would later date Minnie Driver, who played Skylar; then he'd dump her and date Winona Ryder. The original Skylar married the drummer of Metallica.

'How ya like me now?' Thus bellows Affleck's Good Will Hunting character when prole-savant Damon rescues him from humiliation by a strutting Harvard twerp. And surely these days Damon would be justified in a similar outburst. Because after being derided as just another hot actor off the media-industrial production line, he delivered in the most unarguable way: the modestly budgeted Good Will Hunting became Miramax's most successful release, and earned him a joint Best Original Screenplay Oscar and Best Actor nomination. And he co-wrote a part that earned Robin Williams his first Oscar.

But 'How ya like me now?' is the kind of outburst you could never imagine passing Damon's lips. For despite Rourke's fears, this young actor is king of a new breed that eschews arrogance and lifestyle 'statements' in favour of a diligent approach to its craft and an obeisance to the business.

The label Frat Pack, although sometimes applied to an impossibly broad swathe of young talent, does describe the social and professional links between Damon and Affleck and the likes of Vince Vaughn, Matthew McConaughey and Joaquin Phoenix. What's harder to pin down, though, is what it is that unites these Young Turks. Pressed to articulate the group's manifesto, Damon thinks for a moment. 'Everyone is known as nice guys.' He pauses. 'The movie crews talk about that stuff - who's an asshole - and the word on most of the people we know is, "He's a great guy." '

Damon has been reading Easy Riders, Raging Bulls, Peter Biskind's lurid history of the Coppola/Scorsese/ Nicholson-led youth revolution that blew up in Hollywood's jowly face a quarter century ago. The book has not, however, left him feeling nostalgic for more radical times. 'All these guys were revolutionary. Sure, everybody wants to feel part of something bigger than themselves - I wish there was something, but I don't long for it. There's no unified goal now. I'm still grappling with the fact that I can now do the movies I want to do.

'I think a lot of young actors model themselves after Tom Hanks. He's a great professional and such a decent human being. Maybe there's been some kind of cultural shift. . . I don't know.'

Relatively recently, regular-guyness was not coveted by Young Hollywood, with its abundance of malcontented Downeys, Penns, and Cages, who'd titillate and shock with their public transgressions and oversize character flaws, as their unpredictable performances appalled and thrilled. There is no more accurate barometer of the changing times than director Gus Van Sant.

Six years before making the multiplex-friendly Good Will Hunting, he directed the hot River Phoenix/Keanu Reeves duo in My Own Private Idaho, an elliptical movie with a set aflame with rumours both sexual and narcotic. Idaho now looks like a quaint bastion of the actor-as-rebel school: Phoenix burnt himself out, and Reeves was found out. Maybe Affleck and Damon have the right idea after all.

'If the worst thing that happens to me is that I'm considered unhip, I can live with that,' says Damon. Like most of his remarks, this comes with an implied shrug. 'It's always strange when you meet really good actors and they act cool and affected, like the job doesn't matter - as opposed to being total drama geeks. I don't think there's anything wrong with that. You can't just show up on a set and, because you're you, your performance will be good. The work is done when nobody's around. You're disciplining yourself, running at five in the morning. As great as it is to have realised at least part of this American dream in the past six months, I still have to do the work. I mean, I say, "Go hard or go home." If it gets to the point when I go to parties and just show up. . . I'll quit.'

It's the night before the Oscars in March 1998. Damon and Affleck are guests at a lavish party for Miramax's nominees. Squadrons of waiters work the Regent Beverly Wilshire Hotel's ballroom. A long table groans under chocolate bars with wrappers fashioned after Miramax properties, including Good Will Hunting. With nine nominations in the offing, there is a self-congratulatory air among the attendees. We are, after all, privileged courtiers at a Miramax ceremony, in which the nominees play court jesters for company heads Bob and Harvey Weinstein.

Dame Judi Dench (there for Mrs Brown) dons a hard hat to perform Affleck's obscenity-strewn Good Will Hunting speech in which he exhorts Damon (played by Helena Bonham Carter) to flee home-town torpor. Amusing as it is to see Dench say 'pussy', it's not as funny as the all-too-eager audience reaction would suggest.

Affleck and Damon, in partial drag, act out a scene from The Wings of the Dove. When Affleck drops his multi-coloured cape, a brassy voice from the audience tells him to pick it up: 'It's a Gaultier!' The protester is none other than Madonna, sitting with pal Demi Moore. The applause fades and Winona Ryder hugs Damon like a cheer-leader greeting the victorious quarterback. Robin Williams beams proudly, as do the Weinsteins.

The following night, before a global Oscar audience, Damon and Affleck consummate their relationship with Hollywood. Best Original Screenplay: Good Will Hunting. 'It was surreal,' Damon says of the ceremony (to which he and Affleck, the year's most eligible bachelors, brought as their dates their mothers). 'I know "surreal" is an over-used word, but it's the only way I can describe it. When Ben and I went up and saw Jack Nicholson, all those guys we revere, we froze. I mean, last year we were in Toronto filming, watching the awards with Gus [Van Sant], drinking beers, making smart-ass comments. Now we're in the front row - and Billy Crystal's singing about us!'

Two kings, two freaking kings! That is just about as good as it gets in the poker variant known as Texas Hold 'em. And that was the very hand Damon held during the final event in this year's World Series of Poker in Las Vegas. A trumped-up event, yes, but a lucrative one, since each mark must ante up $10,000 if he fancies bellying up to the table at Binion's Horseshoe Casino with the big boys of pro poker. 'Before the event someone asked me, "What're your chances?" ' he recalls. 'I told them, given everything that's happened to me, I wouldn't be surprised if I won.'

So there was Damon, sitting opposite former world champ Doyle Brunson. With that hand. But, ever wary of his table image, Damon kept his cool and bet his remaining $6,200. 'I gotta do it you,' said Brunson, who breezily flipped over. . . two aces! Two freaking aces! (If this were a movie, you'd want to slap the director.)

For Damon the whole thing was just a bit of a lark. His dollars - like much of the money surrounding him this year - were of the promotional sort, as were those of actor buddy Edward Norton; both were bankrolled by Binion's. They were celebrating the completion of John Dahl's Rounders, a gritty gambling flick. Damon plays another genius of sorts, a reformed cardsharp who must rescue his on-the-edge friend and former partner (Norton) from loan sharks.

It is a great film, but not the kind of high-profile release expected to extend Damon's box-office winning streak. And while he appeared in the Spielberg hit Saving Private Ryan, he points out that it was Tom Hanks's vehicle, not his. Damon is aware that he has reached the fragile moment in his career when his 'choices' must justify the initial buzz.

'Maybe all this exposure has made me more famous, but what does that mean? They can make anybody a star for a while - it will always come down to the work you do. But it's not like I want to work hard because I'm worried people will think I'm just a magazine cover boy. I want to do good stuff anyway. Ben and I have a better shot than a lot of great actors. We can do well and respect that or totally blow it.'

Before Damon became a star, his talents were recognised by director Anthony Minghella, who was looking to follow up The English Patient with a new adaptation of The Talented Mr Ripley, a novel from Patricia Highsmith's cultish series about a deceptively erudite liar, killer and all-around psychopath. 'When I met Matt, none of the films that catapulted him into being "Matt Damon" had come out,' says Minghella.

He does not deny that Tom Cruise was the only other candidate for Tom Ripley, a complex, pivotal role (for which Damon gets just $1 million). 'Ripley's talent is for lying and believing the lie with great speed of thought. He's on screen every moment, so if he loses the audience, the film stops. He is kind of pansexual, so it requires an actor with an enormous sense of himself. And Matt is so absolutely male.

It's almost a joke the way he smiles - like someone has stuck a huge mouth on his face. It's beguiling. And it's unusual for a serious, intense actor to have that quality.' Being this sociopathic charmer might be Damon's greatest challenge to date. It will see him playing against his studly sociogenetic type. Besides shedding 20 pounds (he says Minghella wants him to look 'less virile'), he took crash courses in Italian and piano, and listened to jazz of the book's Fifties vintage.

The Big One for Damon, however, is All the Pretty Horses, the adaptation of Cormac McCarthy's best-seller, to be directed by Billy Bob Thornton. When Leonardo DiCaprio - with his $20 million asking price - was wavering about the role, the producers turned to Damon, offering him $5 million. And they delayed filming until he became available. Stakes, as they say, are high.

'I met Paul Newman recently - a huge thrill for me,' says Damon. 'Someone happened to mention All the Pretty Horses. Newman asked, "Who's in that?" I said meekly, "I am." He looked at me and said, "That's a huge responsibility." And I said, "I know." '

A couple of months after the Oscars, Damon is back in LA. He's transforming himself into Tom Ripley - quietly getting on with his Italian lessons and dieting, doing cardio workouts to Coltrane and Parker instead of his usual Springsteen or Bosstones.

At this moment, however, he's driving to 'a friend's house' for his next diet meal. Only with reluctance does he admit that the 'friend' is Winona Ryder. Further discussion of their relationship is strictly forbidden.

Young love might be blooming at Ryder's $2.5 million Beverly Hills pad, but this town's honeymoon with Damon is over. Mention his and Affleck's names here and at best you'll hear mild disdain. 'Too good to be true, those two. Dating Gwyneth [Paltrow, Affleck's girlfriend] and Winona? I mean, really.'

'The paparazzi has gotten pretty intense,' says Damon. 'Ben had to do a U-turn on the freeway recently to avoid them. I've seen people trailing me and had to take, like, three left turns to shake them. I feel fortunate to be so overpaid to do what I do, but when it gets to the point where people hang outside your house. . .' He trails off ominously, sounding vaguely Rourkeish. Despite his potentially thuggish appearance, he avows that he has never sought physical conflict. 'I was definitely not a fighter as a kid. My mother taught non-violent conflict resolution all over the country. I got in one fight at school, and kept hurting the kid when I should have stopped. It scared the hell out of me. I remember the shame. It never left me.

'But I'm moving into a time when I might be more violent. I'm not talking about freaking out at photographers, but I could foresee not having the choice - lines are crossed and it could get dangerous. There's a time when it's OK to fight. I'm lucky - so far, I've never been in imminent danger. But listen. . . There are bigger problems in the world. I don't wanna come off like some griping actor. To not be able to reason with people is just bizarre to me. . . But I'm getting used to it.'