Rooney Mara admits that she was "pushed" over the edge at times in her newest role.

The 26-year-old actress stars as rogue heroine Lisbeth Salander in new film The Girl with the Dragon Tattoo.

Although she coached herself thoroughly in preparation for the role, Rooney did not realise the work would be so taxing in reality.

"I had prepared myself and I knew how emotionally and physically challenging making The Girl with the Dragon Tattoo would be, but the whole project really pushed me," Rooney told British newspaper The Telegraph.

"The physical challenge was probably even more shocking than the emotional, because there were lots of days that we were doing stunts, with many takes, over and over. It was an amazing experience and I know that I have learnt so much."

Rooney had to alter her appearance dramatically to portray Lisbeth. Losing significant weight was a requisite for the role.

"[My character] is meant to look incredibly frail and young and tiny," she explained. "Yet, just like Pippi Longstocking, she can thoroughly defend herself and has a sort of superhuman strength. Both she and Pippi are fighting against bad guys."

Rooney also had to pierce her face for her Lisbeth transformation.

"I think having my eyebrows done freaked me out the most. That really changed the way I looked," Rooney recalled. "I think I was freaked out for about five minutes, then I just let it go and became used to it. The pain wasn't too bad either, with the piercing. I still have the lip-ring, but I am going to take it out."

Overall Rooney really identified with Lisbeth and is really fond of what she represents.

"I really understood [Lisbeth] as a person and that made the whole process a little easier," Rooney said. "Lisbeth resonates with so many people because at some point in their lives they relate to the feeling of being held down by the powers that be, being an outsider, being oppressed. They see it happening to Lisbeth and they want to root for her. They want to see her succeed."