It was previously reported by This Morning's Jeff Brazier that the final five acts would be singing Motown classics, but that has proved incorrect.
All five acts - Janet Devlin, Marcus Collins, Amelia Lily, Little Mix and Misha Bryan - will be performing two tracks on Saturday (November 26) for the first time in the series.
Little Mix have emerged as the bookmakers' new favourites over the past week, following a fall in support from punters for Lily and Collins.
The girl group's backing has soared following their En Vogue cover on last weekend's Movies night.
The X Factor quarter-final airs on Saturday (November 26) at 8pm on ITV1.
Sunday's X Factor results show will feature performances from Xtra Factor host Olly Murs and 'Price Tag' popstar Jessie J.
> Coldplay, Michael Buble, Jessie J for 'X Factor' final duets
Look through a gallery of behind-the-scenes images from the X Factor charity video shoot below: