Michael Bublé performed 'Haven't Met You Yet' with Foo Fighters at the Outside Lands festival.

The 'Learn to Fly' rockers were headlining the music event at San Francisco's Golden Gate Park on Saturday evening (12.08.23) when frontman Dave Grohl spotted a "superfan" in the crowd holding a sign that read "I [heart] Bublé", which just so happened to be the Canadian singer.

Foos' drummer Josh Freese - who replaced the late Taylor Hawkins - used to play for the 'Home' hitmaker.

And Dave quipped: “This mother****** better know the song."

He later joked: “We’ve been doing that thing where people from the audience come up and say ‘I know that f****** song,’ and they walk up and they know the first verse, they don’t know it.

“So this badass mother****** — and I’m not even kidding — flew in today from Argentina to f****** sing that song to you guys. Because there’s no such thing as taking a joke too far.”

The 'Feeling Good' hitmaker performing with the heavy rock band comes after Foos teamed up with Alanis Morissette to pay tribute to Sinead O’Connor at Japan’s Fuji Rock Festival.

They put on a special performance dedicated to the late singer who passed away on July 26 aged 56.

Dave told the crowd: "For a very special reason, ladies and gentlemen, would you please welcome to sing a song with us, Alanis Morissette We’re singing this song for a reason tonight.”

Alanis then added: “For a beautiful woman, with high intelligence and deep empathy, way ahead of her time, who’s no longer with us, this is for her."

They then performed Sinead's track 'Mandinka' - the second song from her 1987 debut album 'The Lion and the Cobra'.

After they finished, Alanis told the audience: "May Sinead rest in some peace."

Sinead was found dead at a flat in Herne Hill, south London just weeks after moving to the city.