Efron: New film was a challenge

Zac Efron has admitted he was worried he couldn't "pull off" his role in The Lucky One.

The High School Musical heartthrob plays a US Marine in Scott Hicks's big-screen adaptation of the Nicholas Sparks novel and confessed he had his doubts at first.

He said: "Initially, I wasn't convinced I could pull this off, but the more I thought about it, and the more I talked to Scott, I realised if there was ever going to be a chance to play a role so different from what I've played before, this was it. I knew that it would be a challenge, but that's where the fun comes in."

Zac's character is suffering from post-traumatic stress disorder, and to make sure he was doing the part justice the actor met with real Marines.

He said: "It was like stepping into a different world. They were very normal guys other than their posture and the way they present themselves: they stood with a purpose, they had laser focus and never broke eye contact.

"They had immense dignity. Never once did they let on how traumatising it was until they started telling their stories, and even then it wasn't weepy, you could just see it in their eyes that they had been there and experienced some pretty gruesome things."

Zac, 24, also had to undergo a physical transformation, with his floppy, boyish hair replaced by a buzz cut.

"I have never had it that short. I didn't know if my head had bumps on it," he smiled. "It was pretty symbolic cutting it all off. Boy, was that weird! But it was a really great feeling."

:: The Lucky One is in cinemas now.