Britney's VMA "Comeback?"

Britney lip-synched the three-minute show-opening performance of her new single "Gimme More," wearing nothing but a sparkly black bikini and ill-fitting blond weave.

Britney, looking tuned out from her own performance, could barely keep time to the music and by the end wasn't even mouthing the words to her own song - while getting groped from behind by overmuscled male models and out-danced by the backup dancers.Cuts to the audience revealed fellow artists rolling their eyes and clearly engaged in other happenings in their surroundings.

50 Cent looked like he might have just thrown up in his mouth, and Rihanna was flat-out laughing to a table guest.MTV officials had warned the pop tart to keep it clean for the live Las Vegas broadcast. Britney was told that if she acted out before yesterday's sound check she could be eliminated from the show.

So the mom of two played it safe, taking baby steps around the stage instead of showcasing her signature dancing skills. She didn't come close to anything as scandalous as her open-mouth kiss with Madonna at the 2003 VMAs.

Host Sarah Silverman was rooting for Britney before the show on the red carpet as were many of the two time mom's peers.

"I'm excited to see Britney," she told the Daily News. "She always brings it. I think she'll do fine."

However, Silverman didn't spare Spears in her opening monologue, saying, "She is 25 years old, and she has already accomplished everything she is going to accomplish in life."