LAS VEGAS — Somewhere, Kevin Federline is laughing. An out-of-shape, out-of-touch Britney Spears delivered what was destined to be the most talked about performance of the MTV Video Music Awards — but for all the wrong reasons.

Kicking off the show Sunday night with her new single, "Gimme More," Spears looked bleary and unprepared, much like her recent tabloid exploits on the streets of Los Angeles. She walked through her dance moves with little enthusiasm. It appeared she had forgotten the entire art of lip-synching. And, perhaps most unforgivable given her once-taut frame, she looked embarrassingly out of shape.

Even the celebrity-studded audience seemed bewildered. 50 Cent looked at Spears with a confused expression; Diddy, her new best friend, was expressionless.

Some comeback.

The VMAs was hoping to reinvent itself on Sunday. After suffering poor reviews and a decline in ratings over the last few years, MTV moved the show to Las Vegas' Palms Casino, shortened the show from three hours to two, and changed the show's setup to focus more on performances than awards.

To that end, Justin Timberlake and Timbaland, Kanye West, Fall Out Boy and the Foo Fighters were each hosting four separate suite parties, where much of the show's performances would be held.

Thankfully, after Spears' dismal start and a lukewarm intro by comedian Sarah Silverman, the show rebounded. Timberlake's suite was packed with revelers, alcohol and eight lingerie-clad stripper types on raised platforms. Before he accepted the Quadruple Threat of the Year award at his suite, the DJ summoned the partygoers to watch the monitor and go crazy if Timberlake won.

He did, they did, and Timberlake said: "I want to challenge MTV to play more videos!" Then he was whisked away by bodyguards and disappeared. He later won male artist of the year, and hit home on that point: "We don't want to see the Simpsons on reality television" — apparently he's not a fan of either Jessica or Ashlee's MTV shows.

Meanwhile, Rihanna won Monster Single of the Year for her ubiquitous hit "Umbrella," and Beyonce and Shakira won Most Earthshattering Collaboration for "Beautiful Liar." Beyonce's shimmering gold dress barely contained her top; immediately after she picked up her trophy, she asked an assistant backstage to help fix her dress, apparently to prevent a wardrobe malfunction.

Other performers were appearing on the show's main stage, in front of an industry-only audience seated at tables, like at the Golden Globes. Chris Brown gave one of the evening's most extravagant performances — a dance-centric, eye-popping spectacle that channeled Michael Jackson, right down to a brief "Billie Jean" imitation. Later. he was joined by Rihanna, who performed her monster single.

While Spears' performance was a showcase, others were delivered in snippets: Akon crooned a bit of his "Smack That" before an award was announced, while the cameras zoomed in on performances from Fall Out Boy and the Foo Fighters mid-performance in their suites, giving viewers the sense that they had happened upon an intimate concert. Cee-Lo delivered a rocking version of Prince's naughty classic "Darling Nikki" in the Foo Fighters suite; Soulja Boy was showing Kanye West his "Crank That" dance in West's suite.

Timberlake and Timbaland's joint suite looked like the most exciting — T.I., buffeted by pole dancers, delivered a rousing version of "Big Things Poppin"' while 50 Cent stopped by to perform "Ayo Technology" with Timberlake and Timbaland.

Not to be outdone, T-Pain and West danced high atop Las Vegas in one of the Palms' balcony suites as celebrated "The Good Life." And Lil Wayne, doing double duty in the Fall Out Boy suite, was particularly animated during their joint performance.

But the TV audience never got full views of those performances, though the network promised viewers more via its Web site and other "remixed" versions of the show. That might have been the purpose — to whet the audiences appetite for repeat viewings by promising glimpses of what they missed during the traditional broadcast.

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