Promotional shot of Robert Pattinson for "Cosmopolis"Google Images

The British heartthrob stars in David Cronenberg’s ‘Cosmopolis’ and although he is a huge fan of the director and had promised to do anything he asked, he drew the line at frontal nudity.

Robert is quoted by Metro France as saying: "Five minutes before we filmed, David told me, 'I want to see the bottom of your balls on the top of the frame.' At the moment, I reminded myself that I would do anything for him. So I went back to see him and told him that wouldn't happen.

"He took it really well. At the start, it's a very bizarre scene that you won't see again in another movie, I promise."

While he enjoyed making the movie – based on the novel by Don DeLillo – ‘Twilight Saga’ star Robert admitted he was anxious he wouldn’t be good enough for the role.

He said: "I spent two weeks in a hotel room worrying and confusing myself.”

Robert is currently at the Cannes Film Festival where he attended the red-carpet premiere of girlfriend Kristen Stewart's film, ‘On the Road’ on Wednesday (23.05.12) and the couple are also expected to attend last night’s screening of ‘Cosmopolis’ together.

 Here's the trailer: