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...

LAS VEGAS — 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 comeback single, “Gimme More,” Spears looked bleary and unprepared.

She walked through her dance moves with little enthusiasm. It appeared she had forgotten the entire art of lip-syncing. And she looked embarrassingly out of shape.

Even the celebrity-studded audience seemed bewildered.

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The Video Music Awards had better luck with their own reinvention.

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 setup to focus more on performances than awards.

Justin Timberlake and Timbaland, Kanye West, Fall Out Boy and the Foo Fighters each hosted separate suite parties, where many of the show’s performances were held.

After Spears’ dismal start and an awkward, off-color intro by comedian Sarah Silverman, the show rebounded with several exciting performances.

(There was even more drama in the audience: An off-camera fight broke out between Pamela Anderson exes Kid Rock and Tommy Lee, leading Diddy to remark: “It’s not just the hip-hop artists that sometimes have a problem.”)

Before Timberlake accepted the Quadruple Threat of the Year award at his suite, the DJ summoned 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.

Timberlake was the night’s big winner, with four trophies. After accepting the award for Male Artist of the Year, he jabbed at MTV again: “We don’t want to see the Simpsons on reality television” — an apparent reference to Jessica’s and Ashlee’s MTV shows.

Meanwhile, Rihanna won the coveted Video of the Year for her metallically inspired “Umbrella.”

The song also won Monster Single of the Year.

Beyoncé and Shakira won Most Earthshattering Collaboration for “Beautiful Liar.” Beyoncé’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 appeared on the show’s main stage, in front of an industry-only audience seated at tables.

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.

Alicia Keys had the evening’s most rousing performance, debuting her new song “No One” and then an inspired, choir-backed cover of George Michael’s “Freedom.”

While performances like Keys’ and Spears’ were delivered on the main stage, 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 midperformance in their suites, giving viewers the sense they had happened upon an intimate concert.

Cee-Lo delivered a rocking version of Prince’s naughty classic “Darling Nikki” in the smoky Foo Fighters suite (where a beer bong was in operation as Dave Grohl danced, sang Cure songs, played air drums and posed for snapshots).

Soulja Boy was showing Kanye West his “Crank That” dance in West’s suite.

Though the suites appeared to be chaotic parties, the MTV-cast revelers were carefully organized and strategically placed for the cameras. In another suite, the emcee encouraged everyone to drink and keep the energy up.

Choreographed or not, 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 they celebrated “The Good Life.”

And Lil Wayne, doing double duty in the Fall Out Boy suite after opening the pre-show with Nicole Scherzinger, was particularly animated.

But the TV audience never got full views of those shows, though MTV promised more via its Web site and other “remixed” versions of the show.