Rooney Mara boxing golds gym workout he Girl With The Dragon Tattoo sneakers tights Lisbeth Salander Rooney Mara boxing golds gym workout he Girl With The Dragon Tattoo sneakers tights Lisbeth Salander

Rooney Mara busted her butt during a workout in LA yesterday, and it looks like the starlet is serious about nailing the role of Lisbeth Salander in The Girl With The Dragon Tattoo.

After chopping off her hair and revealing her startling transformation in W mag last month, the actress has started shooting scenes for the film, which also stars Daniel Craig and Robin Wright.

Click after the jump to see what A-list television actor thinks Ms. Mara is "going to be the biggest movie star of her generation"!