A hat-trick of movies in the first months of 2006 have elevated young actor Jake Gyllenhaal into leading man status. But his choice of career was never in doubt. He talks to Steve Pratt about his film industry family and how Paul Newman gave him driving lessons.

After this year no-one will be calling Jake Gyllenhaal one of the most promising actors of his generation. A hat-trick of movies opening in the first months of 2006 will confirm that promise and elevate him to leading man status.

At 26, he's already proved himself one of Hollywood's most interesting young actors since early screen roles as the son of Billy Crystal in City Slickers and of Robin Williams in an episode of TV series Homicide: Life On The Street.

The title role in cult movie Donnie Darko got him noticed and, while he's generally favoured offbeat roles in not-particularly mainstream movies, he did find box office success in the blockbuster disaster movie The Day After Tomorrow.

Brokeback Mountain and Jarhead, both released this month and generating Oscar buzz, reflect his willingness to go where many other young actors fear to tread. He says that when the story and the people involved are as good as they are, he'll do "pretty much anything" and adds, "If you don't believe it, you only have to look at the past few movies I've done and you will understand".

In the gay cowboy picture Brokeback Mountain, he and Australian actor Heath Ledger play Montana men who continue their secret relationship over two decades, despite marrying their sweethearts and raising a family. Then, in British director Sam Mendes' war film Jarhead, Gyllenhaal is cast as a marine sent out to fight in the first Gulf War. His third role, in the film of the play Proof, sees him as a maths student helping a troubled teacher played by Gwyneth Paltrow.

The roles couldn't be more different or do more to display the versatility of someone who was virtually designed to became an actor. His father, Stephen Gyllenhaal, is a director and his mother, Naomi Foner, is a screenwriter. His sister, Maggie Gyllenhaal, is an actress too. He can also claim Jamie Lee Curtis as his godmother and having Paul Newman to give him driving lessons.

His latest screen roles mark important steps forward for him. When it came to playing gay love scenes and going to war, he put his faith in his director and co-stars. "Heath and I trusted each other enough to take risks," he says of their intimate scenes in Brokeback Mountain. "He made me feel comfortable, he made me want to be present, and that's the best thing you can ask for from someone you're acting with."

He had to learn other skills, including learning to ride a horse, for the role. "I came up a month before we started shooting for, as we called it, 'cowboy training camp'," he recalls. "Getting on a bull wasn't too freaky, I trusted the guys to give me a bull that wasn't too rowdy. I learned how to ride horses, how to wrangle sheep, and how to do the cowboy things."

Kissing another man appears to have been more dangerous than riding the bull. Director Ang Lee recalls that Ledger almost broke Gyllenhaal's nose when they went into a clinch such was the enthusiasm of the snog.

To play Anthony Swofford, whose bestselling memoir is the basis of Jarhead, the actor and his fellow actors went to boot camp to learn how to be soldiers. Off came his head of luxuriant hair, replaced by a scalp-revealing crewcut.

It's also noticeable when he removes his shirt that Gyllenhaal got into shape for the part, perhaps conscious of the scene in which he cavorts around wearing nothing but a Santa hat covering his private parts. "If you knew me at all you would understand that there's not a lot of preparation involved in asking me to get naked," he says.

"The training and getting into shape was primarily for the role and that was my real way in. I felt I needed to get in shape to understand the idea of it, not just for that scene.

"It was one of those scenes that, as an actor, you got through and read the dialogue. But the only dialogue that was written in that scene was, 'Merry Christmas'. Then we move on to scenes where there's more dialogue and more fun. I was really more interested in those until I found myself sitting naked in the desert with a Santa Claus hat on my crotch. No real preparation involved and no fear either."

He's not ashamed to admit that he pursues roles that he wants. "I always do that, there wasn't anything special about this one," he says of lobbying Mendes for the Jarhead role.

"Immediately I read the book I fell in love with it. When I heard Sam was directing it, I thought there was no way I was every going to get the part. Then strangely enough and serendipitously I heard a couple of months later that Sam wanted to meet me in a diner in New York City. He handed me this script and said, 'I'm not offering you the part but I want to hear what you think of it'. I read it, told him I loved it and that I wanted to do it and he said, 'heh, heh, of course you do'.

"I'd read with him and I was horrible, because I'm not very good in auditions. Then I didn't hear from him, so I called him on the phone and said I was perfect for this part and would do anything to play it. And he never called me back.

"It continued like that and then a couple of months later I got the part. But it was a long audition process."

Playing at going to war can only hint at the real horror or, as Gyllenhaal says, boot camp put them on the periphery. "We experienced what a marine would experience to become one, then also a little bit of what it's like to wait to fight and a little bit of action, with the exception of the threat of being killed or killing someone ourselves which I think is what it's all about," he explains.

"I don't think we really know what it feels like. You can feel when you put on the uniform and you can feel it when you have your head shaved. I remember putting on the flak jacket and the helmet for the first time, and feeling all the energy in my body turning inwards. I am so not used to having to protect myself like that. I remember that feeling of being sucked in."

He made the most of boot camp, even if he got only eight hours of sleep during the five days they were there. "By the end of it, I said to myself as we were driving back, 'remember this feeling of going back into civilisation because this is the only little taste you're going to get of what it actually feels like'," he says.

Next for Gyllenhaal is the thriller Zodiac with Mark Ruffalo and Robert Downey Jr. David Fincher, who made Seven and Fight Club, is directing this film about a real life serial killer in San Francisco in the late Sixties and early Seventies. "It's a true story and very David Fincher and very good, hopefully," he says.

* Brokeback Mountain (15) is showing in cinemas now. Jarhead (15) opens on Friday and Proof (12A) opens on February 24.