Margot Robbie struggled to get cast in 'Z for Zachariah'.

The stunning Australian actress admits she wasn't considered a big enough international star when she first auditioned for the movie, but eventually got the role after her breakthrough film 'The Wolf of Wall Street' was released.

She said: ''I was actually trying to get the role of Ann in 'Z for Zachariah' before I had done 'Wolf'. But because I hadn't done a large film, I didn't have enough international value to my name to get the film funded.

''So another actress was attached who had been in more bigger budget, commercial films.

''Ironically, you have to do the bigger films in order to make a small film. When I first tried to do 'Z for Zachariah', I couldn't attach enough value to my name.''

Margot is also set to star in the much anticipated DC Comics movie 'Suicide Squad', playing the sexily unstable Harley Quinn.

The blonde beauty admits the shoot, which recently finished, was ''pretty intense''.

She told The Guardian newspaper: ''It's pretty intense. It's always bigger than you think it's going to be. I definitely didn't think it through when I took on the job, but once you're in the midst of it, it's too late to take it back.

''The whole comic-book world has such a huge fan base. But fortunately when you're on set every day, you're with the same crew, and the same cast every day for so many months, that you're kind of sheltered from it. You get a taste of it when you do exterior shoots, like on the streets, and fans line up - you're kind of reminded of how closely people are watching and anticipating it.