Margot Robbie was eager to star in 'I, Tonya' because she loves an ''underdog story''.

The 27-year-old actress plays the role of former American figure skater Tonya Harding in the Craig Gillespie-directed movie, and Margot has revealed why she was so keen to star in the film.

She explained: ''I love gangster films 'cause I love the underdog story. I love watching someone rise up, despite their circumstances. It's always something I feel like I can get behind. And she felt like an underdog, to me.''

The movie tells the story of Tonya and Jeff Gillooly, who hired a man to break the leg of Nancy Kerrigan - Tonya's competitor - at the National Figure Skating Championship in 1994.

The incident ended Tonya's career, but Margot says she admires her character's ''rebelliousnes''.

The Australian star told Collider: ''She had this scrappiness and rebelliousness that is obviously fun, but she was also, in my eyes, really misunderstood. I could see this bravado and this defiance was really just covering a lot of hurt and a lack of love.

''There were so many elements to her that I needed to explore. And then, of course, once I started looking at the online footage, I couldn't believe what she'd gone through and how harshly she was punished.''

Margot expressed some sympathy with Tonya, who pleaded guilty to hindering the prosecution following the attack on her rival.

Margot said: ''She was chasing the American dream and was just about to get it, and the whole thing came tumbling down.

''Skating was her one safe place in the world, and that was taken away from her. I don't care if you think she did it or not, I don't think she deserved that punishment.''