Jessica Alba became a blonde for a day for a new role in the movie "Barely Lethal." It may not be the same kind of commitment Robert De Niro made to his role in "Raging Bull," but for Jessica Alba, known as a stunning brunette, it was enough for people to notice.

Jessica Alba took to Instagram recently to show off her new bright hair. The undercover blonde Jessica posted a selfie from the set of the film on Sunday, Nov. 24, with the caption "#victoriaknox #selfie @barelylethalmovie taking a break btwn takes -hiding out in a rm -all this #action and #stunts r exhausting."

Alba is featured in the upcoming movie "Barely Lethal" which stars Hailee Steinfeld as a 16-year-old assassin who just wants to be normal. Steinfeld signs herself up at a normal suburban high school.

Jessica Alba's new hair was bright blond on the top layer over her dark roots. E! News said made for a beautiful contrast against Jessica Alba's dark eyes and eyebrows.

The very next day, though, Alba was dark all over again. So, either she dyed it back, or was just wearing a wig. She was spotted in Santa Monica on Tuesday her signature brown hair.