On Monday night's live quarterfinals of The Voice, it was like a flashback to 2003.

Not only did Christina Aguilera perform her hit "Fighter" off of her second studio album Stripped, but she also took to the stage looking like a slimmer version of herself.

The star, 31, worked a sexy strapless leotard with a cleavage-baring bustier top and showed off her fishnet stockings-clad legs in the number's booty-hugging hot pants teamed with embellished high heels.

PHOTOS: Christina Aguilera's sexy style moments

She wore her platinum blonde hair straight and sleek and rather than opting for her bright red lipstick, she left her lips nude and sported sultry smoky bedroom eyes.

PHOTOS: Christina Aguilera's body evolution

It's no secret that the singer has done a 180 with her style recently. After filming The Voice auditions in a saucy black, cleavage-baring mini, Aguilera has switched up her wardrobe for the recent live performances, sporting more modest dresses and softer hair and makeup.

PHOTOS: Stars' crazy cleavage

"I've been through my highs, I've been through my lows; I've been through the gamut of all things in this business," Aguilera shared about her look with Marie Claire magazine in February. "Being too thin. Being bigger...It's noise I block out automatically. I love my body. My boyfriend loooooves my body. My son is healthy and happy, so that's all that matters to me."

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