Rooney Mara says she was given a list of challenging things she would have to do to play Lisbeth Salander before she even auditioned for the role in director David Fincher's English-language version of the Swedish-set mystery "The Girl with the Dragon Tattoo."

Determined to nab the coveted part, Mara gamely acquiesced, ultimately earning an Oscar nomination for her searing portrayal of the iconic antisocial computer hacker/investigator with a photographic memory. She lost to Meryl Streep, who played British former Prime Minister Margaret Thatcher in "The Iron Lady."

"The list was just from the casting director to let me know before I went down the long road of auditioning that, if I were to get the part, I would have to become a smoker, go off and sort of be by myself for a year and I'd have to be butt naked. I'd have to do these horrible rape scenes. I'd have to ride a motorcycle," Mara, a 26-year-old New York native, told reporters at a recent press conference in Manhattan.

Based on the late author Stieg Larsson's novel of the same name, the movie focuses on the relationship between Lisbeth and unfairly disgraced journalist Mikael Blomkvist, played by Daniel Craig. The unlikely pair starts out trying to determine what happened to a young woman who disappeared 40 years earlier and ends up chasing down a serial killer.

Fincher, whose film credits include "The Social Network,""The Curious Case of Benjamin Button,""Fight Club,""The Game" and "Se7en," said the key to making a successful big-screen adaptation of "Dragon" was getting the casting right.

"I wanted a very masculine center to the film. I knew the androgynous side of the movie would be carried by Rooney; that was her job. So I knew I was looking for a sort of Robert Mitchum center and then when we had Daniel and that was a fait accompli, we started to look at the other elements. There is this sort of magnetic ... they are sort of unable to be close to one another. [The characters] sort of push against each other. So I started looking at things about Lisbeth that I wanted to see and I didn't see them initially in anyone we were looking at," Fincher said at the press conference.

He then recalled realizing Mara was "right under our noses" while he worked with her briefly on "The Social Network."

Although her talent was obvious, Fincher said he wanted to make sure she could handle the intensity of "Dragon," which includes a brutal rape scene and stunning demonstration of retribution, before he offered her the job. His solution was to have her audition numerous times to see how hard she would work to secure the role.

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"Finally, after 2 1/2 months, the quality that was undeniable and the thing that seemed to be most Lisbethean was she just wasn't giving up. She was indomitable," Fincher said.

Even though Larsson's books and the recent Swedish-language film adaptations of them starring Noomi Rapace as Lisbeth have been so popular worldwide, Mara insisted she didn't worry about living up to people's expectations about what Lisbeth should be like.

"To be honest, I didn't really think about what other people imagined," she confessed. "I knew what I imagined it to be. I had read all three books and I had a clear picture of who this girl was and, luckily, David's idea was pretty similar. I didn't think much about what other people thought of her."

Despite all the challenges playing Lisbeth posed, some might be surprised to hear what Mara thought was the toughest part of the shoot.

"The motorcycle was definitely the thing that I was the least excited about doing," she said. "It's very dangerous."

In addition to sharpening her driving skills, Mara also underwent a physical metamorphosis that included cutting her own brown hair short and dying it black, bleaching her eyebrows, having a dragon tattoo temporarily painted on her torso and wearing only dark, tattered and sexually ambiguous-looking attire.

Asked what she did about her look when the cameras stopped rolling at the end of the day, Mara replied: "The hair was stuck to my head, so there wasn't that much I could do about that and the eyebrows were bleached. The piercings that were real, stayed in. Obviously, I wasn't wearing my wardrobe home at night. I expected people to treat me much differently, but it really didn't happen. The biggest change I noticed was when you look slightly off in that way, people pay less attention to you. Their expectations of you are lowered."

So, how hard was it to shake off the character when the shoot finally wrapped up?

"I think it was harder to leave the whole experience behind [than it was to give up the character]," Mara said. "You work 100 mph for over a year on something and then you wake up one day and have nothing to do. It's hard to come off of an experience where you are incredibly focused and hardworking. It's hard to come off of that."

Co-starring Robin Wright, Christopher Plummer and Stellan Skarsgard, "The Girl with the Dragon Tattoo" was released this week on DVD and Blu-ray.