Amy Winehouse is preparing to perform two numbers at the Brit Awards tonight.

One of the numbers sang by the troubled star, fresh out of rehab, will be Valerie as part of a medley with Ronson, Brit School graduate Adele, and Daniel Merriweather.

But the star, a five times Grammy award-winner, has only one nomination - her cover of The Zutons' Valerie with Ronson is in the running for Best British Single.

Her album Back To Black, the biggest selling album of 2007, does not qualify because it was released in 2006.

Singer Kate Nash, a former student at Croydon's Brit School, is up for three gongs, including best British female, best British breakthrough and best British single for Foundations.

X Factor winner and ex-Brit School student Leona Lewis got four nominations for best British female, best British album for Spirit, best British breakthrough and best British single for Bleeding Love.

Jamie T, from Wimbledon, has been nominated for best British male.

Sharon and Ozzy Osbourne will host the show live on ITV1 from their own on-stage "residence", described as part Addams Family mansion and part Beckingham Palace.

The couple will sit on thrones surrounded by two giant sculptures of dogs and a totem pole featuring a skull and gigantic bat, a reminder of Ozzy's infamous bat-eating incident.

This year's Brits at Earls Court will feature a "glam" stage with gold drapes and a punk stage adorned with a ripped Union Jack.