JOHN LEGEND. Now that is pretty cool, right?!
It's not unusual for a famous face to pop up on the show throughout the series and 'Ordinary People' singer John added his name to the celeb guest mentors our hopefuls have got to meet this time round: Mel B and Emma Bunton, Alesha Dixon and Fleur East, Robbie Williams, Calvin Harris, Little Mix and we're pretty sure we saw a few of the finalists cosying up for a photograph with James Arthur following his performance on the show too.
John will be performing his new track live on The X Factor during Sunday night's results show (23 October), but before he wows us with his vocals, he's been handing out some (no doubt) pretty useful tips and gems of advice to our hopefuls.
He told them: "When I first started I got rejected by every major record label, including the label I am signed to now. It took six years for me to get there. You just need to keep going."
Each of the contestants performed their songs for Diva Week in front of John (you can find out what they are all singing here), but there was one act in particularly that John took a liking to... Four of Diamonds.
Speaking about the girl group, he said: "I really liked Four of Diamonds, I really thought they were wonderful."
Four of Diamonds were a late addition to the live shows, as their mentor Louis Walsh had previously sent them home at Judges' Houses. However, he decided to reinstate the girls to replace Brooks Way - they had left the competition following allegations about Josh's personal life.
The band, made up of, Caroline, 19, Lauren, 22, Yasmin, 17, and Sophia, 19, revealed that after they had rejoined the show, Louis had asked if they were "mad" at him for initially not putting them through.
The girls told Reveal: "When we first met Louis, he asked us, 'Are you mad at me? Have you forgiven me yet?' We were like, 'Erm… we're not sure Louis!' We all sat down and had a really long chat. Louis is very honest. He even admitted he usually hates working with girl bands as they don't usually get on but says he has a good feeling about us."
Louis currently has two acts left in the competition: Four of Diamonds and 5 After Midnight. Louis' third act Bratavio were the first act to be eliminated from the live shows.
The X Factor continues Saturday 22 October on ITV.
Follow us on Twitter @RevealMag for all your celeb, fashion and beauty news!
Fancy winning some GREAT prizes? Check out Reveal Competitions here!