Justin Timberlake appears on the new Foo Fighters album.

The 'SexyBack' singer ran into the group when they were recording their new LP 'Concrete and Gold' at EastWest studios in Los Angeles and quickly hit it off with frontman Dave Grohl, prompting him to ask if he could add his vocals to one of their songs so he had something to boast about to his friends.

Dave said of Justin: ''We'd drink whiskey in the parking lot. He was really, really cool. Then the night before his last day, he says, 'Can I sing on your record? I don't want to push it, but - I just want to be able to tell my friends.' 

The 'Learn to Fly' hitmakers agreed and the 36-year-old star recorded some 'la la la' sounds for one track.

Dave quipped in an interview with Rolling Stone magazine: ''He nailed it. I'm telling you - the guy's going somewhere.''

And Justin isn't the only famous star to appear on the record because Dave asked his friend Sir Paul McCartney to play drums on one track after the Beatles legend requested to work with their producer, Greg Kurstin, during their recording sessions.

Paul initially replied: ''You're crazy, man!''

But he quickly agreed, having previously enjoyed jamming with the band on Dave's 'Sound City' documentary in 2013.

He said: ''Even if it had been banjo, I think I probably would have showed up.''

And the 75-year-old musician impressed the band with his drumming skills, with his first take of two being used on the finished track.

Drummer Taylor Hawkins said: ''You don't generally think of him as a drummer. But he laid that track so f***ing effortlessly. He never even heard the song - Dave kind of explained it to him with an acoustic guitar. And he was like, 'Yeah, yeah. I think I know what you're doing.' ''

Paul had such a great time in the studio, he was keen to do more with them.

Dave recalled: ''He was so f***ing good.

''We played for an hour, then took a break and had bagels and tea. I thought we were done - I didn't want to rag him out - so I was out having a cig, and someone goes, 'Hey, Paul wants to jam some more.' He rounded everybody up, and we jammed for hours: 'Let's write some songs, man!' ''

Paul quipped: ''Well, you know. Once you get the meter running.''