Mary McCartney/MPL Communications; ABC/Fred WatkinsWhen modern rockers the Foo Fighters first announced their new album, Concrete and Gold, earlier this summer, frontman Dave Grohl described the record as “Motorhead‘s version of Sgt. Pepper.” As it turns out, the upcoming album features an actual BeatlePaul McCartney.

In a new interview with ET Canada, Grohl reveals that McCartney “plays drums on one of our songs.” Adds Dave, “He’s a pal. We’ve known him for a long [time]. He’s great. He’s the most wonderful person in the world. He’s a great guy.”

Grohl and McCartney previously worked together on the song “Cut Me Some Slack,” which also featured Dave’s former Nirvana bandmate Krist Novoselic and Foo Fighters guitarist Pat Smear. The track, which features Grohl on drums, appears on the soundtrack to his 2013 documentary Sound City.

Oddly enough, Sir Paul isn’t the secret “biggest pop star in the world” that Grohl recently revealed contributed backing vocals to a Concrete and Gold song, the identity of whom has been the cause of much speculation. Grohl has denied that the mysterious guest is Adele or Taylor Swift, but he won’t reveal the star’s identity.

Concrete and Gold will be released on September 15.

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