Eli Roth gets his acting in

The horror film director goes toe-to-toe with Brad Pitt in the highly acclaimed Inglourious Basterds.

Eli Roth's character of Sergeant Donny Donowitz, one of an elite unit led by Brad Pitt in the new Second World War-era drama Inglourious Basterds, is a meaty one in the Quentin Tarantino film. Known for his unorthodox weapon of choice - a baseball bat - Donny goes on a memorable killing spree at the climax of the film, a climax that's so over-the-top and so off-the-wall.

In other words, typical Tarantino.

"There is no small role in a Tarantino film," says Roth, who spoke by phone about the movie. "... There are good roles and bad roles. And Tarantino writes great roles."

It's a part Roth, 37, says he auditioned for with a cameo in Tarantino's 2007 Death Proof. Even though he's better known as the director of the gory horror films Cabin Fever, Hostel and Hostel II), Roth said his acting made a lasting impression on his director. "We were doing one or two takes, and it was not taken very seriously, as it was grindhouse. It was just supposed to be having fun. But [Tarantino] said, 'You nailed it... I can always cut to you, every take, every time. You got it perfect.'"

When Roth saw just how prominent the part of Donowitz was in the Basterds script, he was floored. "I was, like, 'Wow! This is one of the main guys. He's in every scene with Brad Pitt - nearly every scene. He's his right-hand man.' I said, 'Look, if I'm going to do this, I've got to bring my A game. If Quentin has faith in me that I can do it, I have to push myself harder than I ever have. I have to be like Robert De Niro or something." And how.

Roth bulked up for the part, putting on nearly 18 kilos of muscle, he says. He also spent time in his native Boston, interviewing veterans of the Second World War. "You've got to look in this guy's eyes," Roth says of Donowitz, "and see all the pain and the anger and the fury he's carrying around with him."

He also looks for inspiration from Ben Stiller, who has built a career not just around acting, but also writing, directing and producing. All Roth's hard work on this film - he also directed the black-and-white film-within-a film that is a lynchpin of the Basterds plot - will pay off when people start seeing him as someone who can do it all, both in front of and behind the camera. "I talked to Quentin about that," Roth says, recalling what his friend and mentor told him.

He said Tarantino said: "'Now you have permission to write great parts for yourself, and no one's going to give you [expletive] about it... Because you've proven you can go toe to toe with the best, and you've held your own against Brad Pitt.'"

If Roth is still a little touchy about his acting chops, he gets even more defensive when asked about being pigeonholed as the chief purveyor - maybe even the inventor - of the film genre known as "torture porn", through the three features he has directed and the raft of violent copycat films that have followed.

"It's not that I set out to make that genre," he says, sighing. "but that's what people call it. And people rip me off. Look, imitation is the highest form of flattery, and if people are ripping you off, it means you did something right."

As further evidence, Roth cites the fact that French critic Jean-Francois Raugier of Le Monde identified Hostel as the best American movie of 2006. His work is also the subject of college courses, Roth notes, and academic dissertations about the "subtext" of the blood-drenched films.

When told just how funny that sounds, though, Roth really let's loose.

"I don't know why that's funny," he says, growing agitated. "Why is it surprising? It's surprising because people that use the term 'torture porn' think that they're stupid movies.

And the people that watch them and actually think about them, and think about what they're about, and analyse them realise that they're much smarter and much more subversive than most people give them credit for."