Britney Spears kicked off the 2007 MTV Video Music Awards tonight (Sept. 9) in Las Vegas with a performance of her new song, "Gimme More," decked out in a sparkly bra and briefs, with knee-high black

Britney Spears kicked off the 2007 MTV Video Music Awards tonight (Sept. 9) in Las Vegas with a performance of her new song, "Gimme More," decked out in a sparkly bra and briefs, with knee-high black boots. It was the embattled Spears' first major public appearance in the run-up to the Nov. 13 release of her first Jive album in four years.

Comedian Sarah Silverman promptly came on stage and lampooned Spears' recent travails. Beyonce and Justin Timberlake lead this year's nominations with seven each. The two artists will square off in the video of the year category, with their songs "Irreplaceable" and "What Goes Around ... Comes Around" competing against Amy Winehouse's "Rehab," Justice's "Dance," Kanye West's "Stronger" and Rihanna's "Umbrella" featuring Jay-Z.

At least one VMA weekend performance didn't go off as smoothly. Last night at the Hard Rock Hotel pool, 50 Cent cut short his set after part of the stage began to sag too close to the water.

The rapper had thrown a handful of money into the air but when fans ran to catch it, they put too much pressure on the stage. "Back up," he yelled, before leaving the area. "You're going to get electrocuted."

For more MTV VMAs coverage, visit the Billboard blog at JadedInsider.com.