X Factor bosses prepare for a showdown as Lady Gaga performs in front of 'enemy' Sharon Osbourne

X Factor bosses are preparing for a showdown this weekend as Lady Gaga takes to the stage in front of Sharon Osbourne, who engaged in a public spat with the singer last year.

Sharon wrote an open letter to Lady Gaga, calling her 'a publicity seeking hypocrite', after she criticised her daughter Kelly's show Fashion Police.

With the 'Applause' singer booked to perform on Sunday's live show, producers are said to be worried that the pair will go head to head on live TV.

What began with Kelly suggesting that Gaga had worn covering clothes to the 2012 Grammys due to a secret pregnancy, evolved into a full blown war with mother and daughter Osbourne on one side, and the Artpop artist on the other.

Following Kelly’s comments on her E! show, Fashion Police, Gaga wrote an open letter saying that her show encouraged bullying and was ‘rooted in criticism’.