Simon shares son's favourite song
He is known for his stinging criticisms, but Simon Cowell showed his softer side when he revealed he and his young son Eric share the same favourite song - a tune from The Jungle Book.
The X Factor judges were full of praise for the group Only The Young, who performed the hit I Wanna Be Like You, originally sang by "king of the swingers" King Louie in the Disney classic.
New dad Cowell, who earlier this week posted a video of his nine month-old son Eric drumming along to a One Direction song, revealed the tune was a favourite of his.
He told the contestants: "It is actually my son's favourite song and it is my favourite song.
"The girls have said it all, it is why I love you in this show. You are fun. You are not taking yourselves too seriously. I really hope the public pick up the phones and keep up in because I love you guys."
Fellow judge and former Spice Girl Mel B also revealed she and her three children are huge fans of the group.
She told them: "I like you, you just know who you are and that is why my kids harp on and on about you. I have a three year-old, a seven year-old and a 15 year-old. They are absolutely in love with you."
It was big band week and the remaining eight contestants all performed with a 30 piece band.
For once the judges were singing from the same hymn sheet as they praised Fleur East's closing performance of Jessie J's hit Bag Bang.
Louis Walsh gushed: "It is very simple, we saved the best for last."
Cheryl Fernandez-Versini said: "You are the person in the competition who is an all-rounder - tonight you sang, you danced, you rapped. You gave it everything."
Earlier Andrea Faustini opened the show with a rendition of Summertime, an old X Factor favourite which former winner Leona Lewis covered while on the show.
He won wave reviews from three of the judges, with Louis declaring "he's like a little Pavarotti" while Cheryl said: "You absolutely brought that to life."
But Simon was left less than impressed with the performance, and in particular the Italian's grimaces.
He said: "You are pulling these terrible faces not just during these your singing but afterwards - like you are in pain. I was disappointed."
Jay James was hoping to bounce back from being in the bottom two last week to by performing Frank Sinatra classic New York, New York.
But his rendition got mixed reviews, with Mel B describing it as "almost borderline comical" while Louis said it was "kind of karaoke".
Louis had kinder words for Lauren Platt, 17, who sang a version of Nat King Cole's Smile. He told the young singer: "Singing with a 30 piece orchestra, it is just so effortless. It is like you were born to do this. You are always note perfect, always consistent."
Stereo Kicks changed their song at the eleventh hour to Mack The Knife - and won a standing ovation from Simon and their mentor Louis.
Ben Haenow's version of Cry Me A River won him praise from Mel B, who said: "It was a good performance and a good delivery".
But Cheryl was less impressed, and told him: "You have been so versatile through each week. Tonight, for me, this wasn't your week. You have been Buble-d." - referring to Canadian crooner Michael Buble.
The show is back on on Sunday night, when another act will get voted off.