The act with the fewest votes will be eliminated and won't have the chance to sing for survival and be saved by the judges.
X Factor's decision to take away the judges' power to save an act looks likely to benefit Christopher Maloney and Jahmene Douglas, who haven't been in the bottom two at any point during the series.
Union J are the bookmakers' favourites to get the chop on Sunday.
Pink and Tulisa are the guest performers on this weekend's X Factor.
Watch Digital Spy's interview with Jahmene Douglas at last night's X Factor secret gig: