Harper led the band in a cover of Queen's "We Will Rock You," naturally the first song she learned to play. As her dad put it: "There's another Grohl on the drum set now."
As Harper set herself up on stage, Grohl shared the story behind her surprise performance with the audience:
"About two weeks ago, my daughter said, 'Daddy, I want to play the drums.' And I said, 'Ok— you want me to teach you?' and she said yes. And then I said, 'Do you want to get up on front of 20,000 people in Iceland and play?' And she said yes."
[Via: Mashable | Image Credits]