Harry Styles stepped in for James Corden after the TV star became a father again, just half an hour before his talk show aired.
Corden’s wife Julia Carey had the couple’s third child, a girl, who is sibling to son Max, six, and daughter Carey, three.
The British star, 39, revealed the happy news on Twitter, writing: “Today we welcomed a beautiful baby daughter into the world.
“Both she and her mother are doing great. We can’t stop smiling. Thank you Harry for stepping into host the show at two and a half hours notice.”
Ben Winston, producer of The Late Late Show – which is famous for its Carpool Karaoke segment, wrote that it had been a “crazy day”.
“Our wonderful host James Corden had his baby today with a half hour to go before the show!,” he revealed.
“Congrats to the Cordens. And thanks to the incredible Harry Styles for stepping in literally at the last minute. What a performance with no prep!”
Styles joked to the audience that his time as host would be a “one-time only” event – “unless CBS likes what they see”.
“This is very exciting. Just a half an hour ago, James and his wife Jules had a beautiful baby girl,” the singer said during his opening monologue on the US show.
“Congratulations. In fact, I was just at the hospital before I came to fill in, and she looks a lot like James, mainly because James looks like a giant baby,” he quipped.
Corden and Carey wed in a lavish ceremony, attended by a host of celebrity friends, in 2012.