The sisters are set to become rivals

As speculation that Dannii Minogue won’t be returning to The X Factor reaches fever pitch, her troubles could be about to get worse.

Dannii, 37, who fled home to Australia after struggling to make her mark on the last series, could now be replaced by none other than her own sister.

TV insiders tell NOW that Simon Cowell has lined up Kylie, 40, to appear on American Idol, paving the way for a starring role as an X Factor judge.

A source says: ‘Dannii’s saying she’ll be in Australia until April, but it could be longer.

‘Her experience on The X Factor last year was much more than she bargained for. She’d had a hard time with Sharon Osbourne, but there was nothing more cruel than being constantly compared to golden girl Cheryl Cole.

‘What would really hurt is if her own sister took over from her. Dannii’s always struggled with having to play second fiddle to Kylie.’

A spokesman for American Idol couldn’t confirm Kylie’s appearance, but said there will be plenty of celebrity guests on the ITV2 show.

See the full story about Dannii and Kylie Minogue in Now magazine dated 26 January 2009 – out now!