In an X Factor first, viewers will see the judges take to the stage to perform with their acts during the show's final at Wembley Arena this weekend.
Gary Barlow and his boy Marcus Collins have decided to sing Billy Joel's Always A Woman, while Tulisa Contostavlos is to join her girl group Little Mix for a mash-up of Alicia Keys' If I Ain't Got You and Empire State Of Mind.
Kelly Rowland and Amelia Lily have chosen Tina Turner's River Deep, Mountain High for their duet on Saturday.
'It's going to be more pressured than ever. The acts will be singing in front of 10,000 people - and with their mentors,' a show source tells the Daily Mirror.
'The judges will be nervous as well because the song could be the difference between winning and losing.'
Coldplay, One Direction, JLS, Leona Lewis and Michael Bublé are also lined-up to perform on the star-studded evening.
'Guys can't even thank you all enough for voting for me! I'm so grateful, can't believe I'm In the final of TXF! Love you all so much lilys'!' Amelia, 17, Tweeted after the semi-final results programme on Sunday.
Fourth judge Louis Walsh doesn't have an act in the final.
NEW PICTURES The X Factor final 16 contestants settle into their new house>>
NEW PICTURES The X Factor 2011 Final 16>>
NEW PICTURES The X Factor 2011 Final 32>>
NEW PICTURES Tulisa Constostavlos and Kelly Rowland party before X factor launch>>
NEW PICTURES The X Factor judges launch the 2011 show>>
Esme Riley
