Slimmed-Down Christina Aguilera Covers Up Cleavage on The Voice

On Monday's episode of The Voice it was the judges, not the contestants, who stole the show with their makeovers.

Adam Levine's showed off his shaved head, Cee-Lo donned a bizarre curly wig with an Elvis-inspired red lace-up jumpsuit and Christina Aguilera shocked fans with her conservative (for her) appearance.

After wearing a plunging black dress that revealed everything but her nipples and a wacky "compact-disc hat" during the battle rounds, the 31-year-old singer opted for a flattering long-sleeve zebra-print look. She also went with a a softer hairstyle, but kept her dramatic makeup, rocking glossy red lips and heavy smoky eyes.

PHOTOS: Christina Aguilera's sexy style moments

Perhaps Aguilera's new demure look influenced her opinion of 17-year-old RaeLynn's hip-shaking dance moves.

"Are you allowed to grind your hips like that at that age?" she asked the young country singer following her sexy performance.