Beyonce's triple Oscar performance

Beyonce Knowles will be the singing star sensation at the Oscars later this month - after agreeing to perform three of the five nominated songs.

The chart-topping diva will duet with crooner Josh Groban on 'The Polar Express' theme tune, Believe, as well as the title songs from 'Phantom of the Opera' and 'Les Choristes'.

The Bootylicious sensation agreed to step in for actress-cum-singer Minnie Driver, the original performer of 'Phantom''s Learn to Be Lonely, after the actress refused, saying she had other work commitments.

Beyonce is now said to be frantically working on the song with composer Andrew Lloyd Webber after she demanded the score be adjusted to a higher key, to better suit her voice.

Andrew's wife, Madeline Lloyd Webber, revealed: "Beyonce wants it higher and longer, so Andrew is going to rejig the song for her voice."

Also set to rock the Academy Awards on 28 February are The Counting Crows with their song Accidentally in Love from hit animation 'Shrek 2'.

The performer of the remaining contender, Al Otro Lado Del Rio, from hit biopic 'The Motorcycle Diaries', has yet to be announced.

Previous winners of the best song category include Eminem, Elton John and Bruce Springsteen.