She is famed for her glossy brown locks.
But stunning Jessica Alba has reached for the bottle, debuting a new blonde 'do over the weekend.
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And it was all in the name of work. The 31-year-old is due to reprise her role as stripper Nancy for the hotly-anticipated sequel to 2005's Sin City.
The actress documented her transformation with a series of photos on Twitter.
"Bye bye brown hair," she wrote on August 23, later adding: "Stage 1 – ok it doesn't look that different but it's a process."
Two days later, she posted another picture of her lighter locks with her style team at Robert Ramos of Estilo Salon in Los Angeles posing in the background.
"Stage 2 of Sin City 2 Nancy hair. She got roots that Nancy. Sin City 2," she wrote.
With her new hair colour in place, Jessica hit the shooting range on the following day to practise her skills.
"What a way to start the day – training for a movie is sorta fun," she said.
Clive Owen, Mickey Rourke, Rosario Dawson, Devon Aoki and Michael Madsen will also return for the eagerly anticipated sequel, which is based on Frank Miller's graphic novel series.
Sin City: A Dame To Kill For is scheduled for a 2013 release.