Video: Sinéad O'Connor sings as Conor McGregor enters the Octagon - brilliant fan footage
"There's nothing louder than the Irish. I was telling the Metro police officers - you boys are in for a long night," said Dana White afterwards.
He was right.
"I called Sinéad O'Connor and asked her if she'd ever heard of the UFC? "No," she responded, "but I've heard of Conor McGregor."
"So she was in," White told the press conference after the fight.
"We wanted this thing to look great. To sound great. Sinéad's voice is just iconic and bad-ass and it came off great tonight."
JOE reader Emmet Hayde caught the whole thing on camera and shot this from the rafters. Our favourite fan footage clip yet.