Zac Efron felt intimidated when Nicole Kidman said she was bringing her "A-game" for their sex scenes.

The former High School Musical heartthrob stars alongside Nicole in Lee Daniels thriller The Paperboy.

The film includes a steamy scene which features co-star John Cusack engaging in a sex act while Zac's character watches on.

"That was the first day of filming and Nicole just completely went for it," Zac told Black Book magazine.

"She was telling everyone, 'I'm bringing my A-game. What do you have?"

After numerous roles in teen movies such as 17 Again, Zac set out to find a project with more depth.

Despite his initial apprehension, the 24-year-old knew the movie was right for him and he even managed to enjoy his scenes with the Hollywood beauty.

"I've never been so scared in my life, but that moment affirmed this movie was everything I set out to do," he gushed.

"The love scenes with Nicole Kidman were the highlight of my life. Every scene felt like I was in Moulin Rouge."