Dermot O'Leary's father-in-law is their Max and Harvey's biggest fan

Max and Harvey Mills have revealed their "biggest and oldest fan" is none other than \'The X Factor: Celebrity\' host Dermot O\'Leary\'s father-in-law.

The YouTube sensations are favourites to win the ITV singing competition tomorrow night (30.11.19) with hundreds of youngsters voting for the 16-year-old twins, but the duo admitted their popularity isn\'t limited to their own generation.

Harvey told the Daily Star newspaper: "The other night Dermot texted one of the production team to ask if we could go and meet his wife\'s parents! His father-in-law is out biggest and oldest fan. He\'s 87."

Max added: "We were like, \'What is happening? Is this some sort of joke?\' It was just so surreal. But they were both so lovely."

The singing duo are up against Megan McKenna, Jenny Ryan and V5 - formed of social media influencers Alondra Martinez, Renata Vaca, Sofia Oliveira, Wendii Sarmiento, and Laura Buitrago - in the final, and their school friends have teased them about the upcoming challenge.

Max explained: "Our school friends are all very supportive and have been texting us every week."

Harvey quipped: "Now people are saying that we have to win and if we don\'t then they\'ll stop being friends with us!"

Meanwhile, \'The X Factor: Celebrity\' final will also see the return of The Pussycat Dolls.

The \'Don\'t Cha\' hitmakers - including Nicole Scherzinger, Ashley Roberts, Kimberley Wyatt, Jessica Sutta, Carmit Bachar and Melody Thornton - will be getting the band back together for a special performance as Simon Cowell\'s talent show comes to an end.

Judge Louis Walsh confirmed the exciting news on ITV\'s \'Lorraine\' on Monday (25.11.19) as he simply said: "The Pussycat Dolls are the guest! There\'s an exclusive for you."

The hugely popular girl group went on hiatus in 2010, and it was recently reported that Nicole was keen to get them back together for \'The X Factor\' to kick off a huge world tour.