Actress Naomi Watts may have played various roles, but she claims that her role in her upcoming film on Princess Diana, is the toughest of all.

The actress will play the Princess herself in the film, that will show her romance and break-up with Prince Charles. Initially, the actress turned down the role several times. But then the idea of going through this transformation and telling the story of someone who is wildly famous, is what made her go for it.

Directed by Oliver Hirschbiegel, the film which will show the last two years of the life of Diana, Princess of Wales, is scheduled for release on 20 September 2013.