Troubled pop star Britney Spears has 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 Sunday night’s event in Las Vegas with her new single, Gimme More, Britney looked bleary and unprepared, much like her recent tabloid exploits on the streets of Los Angeles.

Out-of-synch lip-synching, a tacky stripper-style costume, sluggish movements and a noticeable paunch in place of her once-taut stomach reminded everyone that the old Britney is not quite back yet.

At times throughout the performance Britney appeared to stop singing altogether.

Even the star-studded crowd seemed bewildered. 50 Cent looked at the pop princess and appeared confused by what he saw, while P Diddy, her new best friend, was expressionless.

US blogger Perez Hilton said: “She blew it. Everybody knows Britney lip-syncs, but that’s because she dances so much. She barely even danced in this.

“It was so bad. It was painful. It was embarrassing.”

Britney put her music career on the back-burner in 2004 when she married Kevin Federline and gave birth to two children, Jayden James and Sean Preston.

The VMAs was hoping to reinvent itself 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 set-up to focus more on performances than awards.

Britney’s ex Justin Timberlake bagged two gongs at the event for Quadruple Threat Of The Year and Male Artist Of The Year.