Louis Walsh reportedly arrived at The X Factor USA auditions with little idea of who Demi Lovato was, but the pair have become firm friends after the Irish music mogul's guest stint on the judging panel.
With Simon Cowell in bed with bronchitis, the X Factor UK judge was flown across the Atlantic to join Lovato, Britney Spears and LA Reid behind television's most famous desk.
Demi said after the Kansas City tryouts: "There is only one Simon… But Louis killed it tonight".
A source added: "Louis didn't know much about Demi when he first arrived but they spoke a lot and he liked getting to know her more".
The Westlife mastermind also got along swimmingly with Britney.
"It looked like he got on well with Britney and was talking to her a lot," the insider revealed. "She was clearly very comfortable next to him and he's a big Britney fan anyway."
Britney herself said: "I love Louis, he's really fun and I think he's absolutely adorable. I do miss Simon a little bit though!"
The auditions will broadcast this autumn.
Louis' wild hair steals the show in the UK!