Beyonce to perform on X-Factor final?

Acording to Beyonce's #1 fansite, Beyonce will be performing on the X-Factor final on December 13th! They say Beyonce will perform a duet with one of the finalists (the way Take that performed with Leona Lewis on the final)

I really hope this is true because Britney Spears will be performing at the Britney week and Leona Lewis will be performing in a few week... Britney, Beyonce, Leona and Christina Aguilera are out top favourite singers ever so it would be amazing if they did.. all we need is for Christina Aguilera to perform too!