January Jones has confessed to feeling "intimidated" by her superhero alter-ego's revealing outfits.
The Mad Men star plays sexy mutant telepath Emma Frost in Matthew Vaughn's X-Men: First Class, a change from prim and proper Betty Draper in the hit TV series.
"The costumes are insane, it's a lot of very body-conscious stuff; if you look at the comic book, she's barely dressed - she's got quite the bod, which is very intimidating," she told Hero Complex.
January said she has been encouraged to avoid the gym so she can keep her curves, yet she wanted to tone up for the part.
"I'm thinking, 'I'm supposed to be doing crunches on the plane. How am I gonna get buff in one day? I'm a petite person, so I didn't want to go into a strict workout and eating regime," she explained.
"I would have disappeared entirely, and she's very busty, very voluptuous, so I didn't want to get rid of any of my curves."
The 32-year-old aims to do the character justice on the big screen, and has done her research.
"I wanted to know as much as I could about her so I wasn't disappointing anyone. I'm sure I will still disappoint someone," she added.
James McAvoy takes over from Patrick Stewart to play Professor Charles Xavier in the prequel, with Michael Fassbender as Magneto and Nicholas Hoult as Beast.