Jen Aniston Dazzles in Sparkly Cocktail Dress

Credit: Fred Duval/FilmMagic

Quick change!

Jennifer Aniston switched from the racy black leather number she wore earlier on Wednesday to a demure shimmery cocktail dress for the evening premiere of Horrible Bosses in London.

The 42-year-old actress left her beloved collection of LBDs at home, opting for an embellished halter design by Valentino that hit at the knee (as opposed to her usual thigh-grazing hemlines). She accessorized with a pair of Tom Ford peep-toe heels.

PHOTOS: See more pics of Jen in dress from PopSugar

Aniston has been getting a lot of buzz for her role in the flick, in which she plays a dentist who sexually harasses a male employee.

"I had a blast. I got to be as crazy as a loon and not worry about the repercussions. I loved getting to play an absolutely insane crazy sexual character," she tells Us Weekly.