Would it be an A-list actress like Scarlett Johansson or Natalie Portman, or someone completely unknown to audiences?

For Fincher, the Oscar nominated director of "The Social Network," the answer was never clear cut. Little did he know that his eventual choice, Rooney Mara, was under his nose the whole time. Fincher had cast her as the girlfriend of Facebook billionaire Mark Zuckerberg in "Social Network."

"Dragon Tattoo" opens across the United States on Wednesday. It is based on Swedish author Stieg Larsson's first novel in his mega-popular Millennium Trilogy series, and Fincher's film follows a Swedish movie version of the book.

To some, it may seem that Mara had a Hollywood "in" to play the troubled Salander, who helps a disgraced investigative journalist (Daniel Craig) solve a case. However, the 26-year old actress told Reuters it was quite the opposite.

"I think he was happy with the work I did in 'Social Network,' but because of that work, I think he thought I wasn't quite right for the part" of Salander, she said.

Her role in "Social Network" was that of a polished college girl, and she hadn't tackled any major starring roles in the movies. Moreover, her upbringing in a large and well-to-do family was far removed from Salander's dark and lonely life.

Admittedly, Fincher told Reuters Mara's casting was "a slow realization," but ultimately he found her to be an "emotional hanger" who wore the character like a suit of clothes.

Salander, with her dramatic storyline and elaborate look that includes numerous piercings, tattoos and closely cropped hair, is no doubt a Hollywood breakout role for Mara. Last week, she was nominated for her first Golden Globe Award in the best dramatic actress category.

Yet Mara shies from calling "Dragon Tattoo" her big break.

"I think everything I've ever done has led me to the next thing, so I can't say that I have one thing that I feel is a bigger break than the rest," she said.

CAREER TURNING POINT

Still, the Salander role is the most high-profile part Mara has ever tackled, and it may be the most demanding, too.

It required her to learn to ride a motorcycle and skateboard, and she underwent a physical transformation when she chopped off her long hair, colored it black, bleached her eyebrows and underwent numerous piercings all over her body.

In addition to the physicality of the role, there was just as much -- if not more -- emotional trauma to display including scenes of Salander being assaulted by her legal guardian.

But there is a payoff. The actress now finds herself in the enviable position of being on numerous filmmaker lists for major studio projects. She's already committed to star opposite Ryan Gosling and Christian Bale in filmmaker Terrence Malick's "Lawless" that will shoot next year.

Her Hollywood career is a far cry from the sports world in which her family is steeped. Her great-grandfathers Art Rooney and Tim Mara founded professional football's Pittsburgh Steelers and New York Giants, respectively. Both her uncle and father work for the Giants.

Mara says her family's sports background does not inform who she is today, even though she dropped her first name Patricia in favor of her middle name Rooney. But she recognizes that her family and its history in football is unique.

"I certainly appreciate it very much. I grew up surrounded by people who knew what they loved to do and worked very hard at that, so that was definitely instilled in me," she said.

Mara recalled a childhood of going to the theater and watching old movies, more than football. She moved to Los Angeles after her big sister, actress Kate Mara ("127 Hours"), was already living and working there.

Small parts came her way in guest-starring roles on TV's "Law & Order: Special Victim's Unit" and "E.R." Film roles included "Youth In Revolt" with Michael Cera, "Tanner Hall," and "A Nightmare on Elm Street" with Jackie Earle Haley."

Twenty-five days after Fincher turned in the finished version of "Social Network," he and Mara flew to Sweden to start shooting "Dragon Tattoo."

"This movie, especially, I feel like I learned so much from it," Mara said. "First of all, it shot for so much longer than anything I've ever worked on. And in between all the actors and the things I learned from David, I've grown so much."

Though it's too early to tell if the movie's producers plan on shooting the next two installments of the film, the actress already is mentally on board.

"I look very much forward to it," she said with certainty.

(Editing by Bob Tourtellotte)

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