X Factor finalists to duet with their mentors

Kelly Rowland, Gary Barlow and Tulisa Contostavlos will all have to take to the stage on Saturday's show at London's Wembley Arena to perform with the finalists.

Kelly and Amelia are taking on Ike and Tina Turner's River Deep, Mountain High, while Tulisa and Little Mix will perform a medley of Alicia Keys hits If I Ain't Got You and Empire State Of Mind.

Gary and Marcus have reportedly been rehearsing several songs, including the Take That hits Never Forget and Greatest Day, but are still not sure which one they will perform.

A source told British newspaper the Daily Mirror: 'It's going to be more pressured than ever. The acts will be singing in front of 10,000 people - and with their mentors.

'The judges will be nervous as well because the song could be the difference between winning and losing.

'And on top of that, Simon Cowell will be watching from LA. So the judges are almost auditioning for their places on next year’s show as well.'

Coldplay, Leona Lewis, Michael Buble, JLS and One Direction and Westlife are all set to perform as well.