The X Factor finalists are teaming up with their mentors on stage this weekend as they bid to win the show.
Judges Kelly Rowland, Tulisa Contostavlos and Gary Barlow will perform with the three acts during Saturday's edition of the ITV1 programme.
Marcus Collins, Little Mix and Amelia Lily will battle it out to be crowned the winner on Sunday night's finale.
They are said to have been rehearsing for days with members of the panel. The fourth judge, Louis Walsh, has none of his acts left in the competition.
Gary told a press conference in Wembley, north London, today that he had planned the duet of Billy Joel's She's Always A Woman so Marcus would get the limelight.
He said: "For the first time ever we have three judges duetting with their acts on Saturday night so thank God Louis didn't get an act in the final."
Louis joked that he wanted to team up with X Factor failure Johnny Robinson in a duet he said would be like Save Your Love hitmakers Renee and Renato.
Kelly and Amelia will duet on the soul classic River Deep - Mountain High, while Tulisa and Little Mix perform Alicia Keys If I Ain't Got You and Empire State Of Mind.
A show spokeswoman said: "This is a first for The X Factor. Our final weekend at Wembley Arena is going to be our biggest ever and the judges performing with their finalists is an exciting addition to the weekend."
This year's competition will end with performances by Coldplay, Leona Lewis, JLS and One Direction. Last year the series ended with slots by Rihanna and Christina Aguilera, but the raunchy performances brought a flood of complaints and were criticised by TV regulators.