5:51pm PT by Billboard Staff
Watch Paul McCartney and Dave Grohl Play a Beatles Classic
Paul McCartney fans got a double dose of rock royalty Saturday night when Dave Grohl joined him onstage at the O2 Arena in London.
Grohl appeared unannounced midway through McCartney's headlining set; grinning, he joined Macca to perform the Beatles hit "I Saw Her Standing There," which they'd previously performed together at the 2009 Grammy Awards.
Watch McCartney and Grohl rock out below:
This story first appeared on Billboard.com.