Grohl invited the former Beatle to, "jam with some mates." But, with Grohl on drums, Novoselic on bass, and guitarist Pat Smear (who toured with Nirvana in their final months), McCartney is essentially filling the spot that was once reserved for the late Kurt Cobain. McCartney said, "somebody whispered to me: 'That's Nirvana. You're Kurt.' I couldn't believe it."
Grohl and Novoselic have played together a few times since the demise ofNirvana. Novoselic has occasionally contributed to Grohl's band, Foo Fighters. The duo also recorded together for the soundtrack to Grohl's upcoming Sound City documentary.
McCartney and Grohl performed together at the 2012 Grammys.