Sarah Brightman arrive at Classical Brit Awards Launch Party held at the Mayfair Hotel, London, England - 08.04.08

The odd couple will perform a duet, which will end the hour-long ceremony on Friday night (08Aug08) at the National Stadium.

The theme tune is such a big secret, ceremony officials have refused to release the title of the track.

It's not the first time British singer Brightman has been chosen to sing an Olympic theme - she dueted with Jose Carreras for the 1992 anthem Amigos Para Siempre at the Barcelona Games in Spain.

Source: WENN