Brad Pitt was in a "no-shame zone" when he had to sing for a movie role.

The Hollywood hunk teamed up with close friend Matt Damon to play Bill and Will the Krill in the new animation Happy Feet Two.

The krill perform a song in one scene and while Matt was happy to show off his vocal talents Brad was lacking in musical ability.

However, the star decided to banish any nerves and give the track everything he had.

"There were really very free, working off each other, because they know each other so well. Matt Damon can sing, and Brad Pitt made it really clear upfront he couldn't. But Brad just said, This is a no-shame zone: I'm just going to go out there and give it a go,' and he did remarkably well," explains director George Miller.

Matt had a great time voicing his role for the animation. He loved spending time with Brad and the pair left the studio feeling euphoric.

"Brad and I were doing stuff we've never done in any kind of movie, animated or not. We left there thinking, Now what was cool!'" Matt revealed.

Brad and Matt both have young families, and their children influenced them to take part in the film. Matt's daughter was such a fan of the original 2006 Happy Feet movie that she begged her father to accept the role before he had even read the script.

"Do not underestimate the power of children to pester their parents to act in a film," explained producer Bill Miller. "Matt Damon told us he hadn't even cracked open the screenplay to Happy Feet Two before his daughter said, Dad, you're doing it.' Matt really had no choice."