McElderry is the bookie's favourite to win
One of the three remaining X Factor finalists will be kicked off the show later as the competition nears its end with a star-studded guest line-up.
George Michael is set to perform with teenager Joe McElderry while Essex mum-of-one Stacy Solomon will sing with crooner Michael Buble.
Robbie Williams is back to duet with Olly Murs, 25, weeks after a shaky comeback performance on the ITV show.
An audience of 20 million is expected for the first-leg of the final.
Rating for this series have, so far, peaked at more than 15 million.
One of the singers will be voted out later, with the two remaining finalists competing on Sunday for a recording contract.
McElderry, 18, from South Shields is currently the bookie's favourite to walk off with the million pound deal.
Down-to-earth Solomon and Murs have picked up lots of fans
He will perform Don't Let The Sun Go Down On Me alongside George Michael, and the tracks Sorry Seems To Be The Hardest Word and Dance With My Father - the song he sang for his first audition.
Solomon will sing Wonderful World, Queen's Who Wants To Live Forever and will duet with Michael Buble on Feeling Good.
Murs takes on one of Robbie William's best known songs Angels and will also perform Fool In Love and Stevie Wonder's Superstition.
Last year's winner, Alexandra Burke topped the charts with her debut album Overcome in October this year and has had two solo number one singles.
More than 13 million viewers tuned in to watch her in the final.
Leona Lewis, the 2006 X Factor winner, remains the most successful in the show's history selling more than seven million albums worldwide.
But not all winners have enjoyed the same success. Leon Jackson, from West Lothian, won the competition in 2007.
He was dropped after his debut album charted at number four in the UK.
The winner of series one, Steve Brookstein, was also dropped eight months into his contract despite a number one single and album.
Meanwhile, X Factor judge Simon Cowell has criticised an internet campaign to prevent this year's winner from having the Christmas number one single.
A group set up on social networking site Facebook is calling for people to buy US alt-rock band Rage Against The Machine's 1992 single Killing in the Name.
The group has more than 600,000 members.