Robert Pattinson spent two weeks "worrying" about playing a billionaire in Cosmopolis.

The Twilight actor locked himself in his hotel room for a fortnight prior to shooting the drama movie - which sees him play Eric Packer, a multi-billionaire Wall Street CEO - but he was calmed down by director David Cronenberg who reassured him that his talent would bring out the best in his alter-ego.

"The preparation, I kind of spent two weeks in my hotel room worrying and confusing myself. I remember the weekend before we started shooting, I called David to talk to him about it, to ask him 'one question' like, 'Want to talk about the movie for a bit?' So then I went round to David's house and he said, 'It doesn't really matter. Let's just start, then something will happen.' I think Eric Packer's impossible to approach like you would a normal character."

The 26-year-old star felt the film script was more like lyrics from a song which he found "easier" to comprehend and as a result he didn't want to alter any of the words.

"What I liked about the script initially was its lyricism and just the rhythms of it. I mean, normally when you do a movie, you can kind of blur the lines and you can make it your own. But with this, I didn't want to change a single word, not even the punctuation. That made it easier, it's like you're doing a song instead of a movie. It was interesting, it freed you up. If you're trying to do something in a cerebral way, it becomes about ego and it's silly at that point. Actors aren't supposed to be intelligent," he added.