TORONTO - Actor Sam Worthington is still reeling from the success of James Cameron's Oscar-winning blockbuster "Avatar," in which he plays the lead character Jake Sully.

"It already changed my life making it so then when it all starts coming out and all these other jobs started coming out, it's overwhelming," the amiable Aussie star said in an interview Tuesday at the Toronto International Film Festival, where he can be seen in two features, including "The Debt."

"And you handle it hopefully with some level of sensitivity and you just try and keep your work up and you try to give an audience their 16 bucks worth and that's the main thing.

"Try to do challenging stuff working with challenging people so you've enjoyed the day."

"The Debt," directed by John Madden ("Shakespeare in Love"), was certainly a challenge.

Worthington said he did loads of research and went through rigorous physical training to play one of three young Mossad agents on a covert mission to capture a notorious Nazi war criminal in 1965.

Jessica Chastain and Marton Csokas co-star as the other young agents who are seen in flashbacks. Playing the same characters in modern day are Helen Mirren, Tom Wilkinson and Ciaran Hinds.

"The Debt," set for release in theatres in December, is one of several projects Worthington has been juggling lately.

In April, he starred in "Clash of the Titans," at the Toronto film fest he can also be seen alongside Keira Knightley in "Last Night," and next year he's due to star in at least two more features.

"I've always said I'd like to do movies that I would go and see," he said, adding he never can tell if something's going to be a hit.

"No one knows the goose that laid the golden egg, everyone wants that, and if you knew that you'd be making zillions of dollars as a studio executive."

But didn't he know "Avatar" would be such a smash?

"No, no, I needed a job. And it's with James Cameron, so you're never going to say no, are you?" he said with a laugh.

"No one knew how big it was. We were making a 3D movie with a guy who hadn't made a movie in 10, 11 years, about big blue cats -- how the hell is that going to work?

"We were looking at each other like we were mad men, you know."

Worthington said even Cameron had some doubts about how the final product would look.

"Even he told me on the plane before it came out, we were selling it and even he's going: 'I don't know if it works, if it doesn't, it doesn't,"' Worthington recalled.

"And I said: 'Well, I'll stand on the front line with you boss, that's it."'