In their first appearance on the 'Late Show With David Letterman' this week, the Foo Fighters kicked things off in spectacular fashion. Inviting his good friend, country rock star Zac Brown, to the stage, Dave Grohl and company tore through a raucous cover of Black Sabbath's 'War Pigs.' Check out their performance from last night (Oct. 13) in the video above.

The rendition wasn't perfect, but that's always been part of the allure of real rock and roll, right? When a song gets too over-polished or too right, it gets uninteresting and boring. But the Foos and Brown put together a massively entertaining spin on a widely-covered tune, and even Letterman was impressed. "Zac Brown, Black Sabbath and the Foo Fighters. I don't know," he said at the end of the song, obviously blown away. "What do you kids want from me?"

The Foo Fighters will be Letterman's musical guests all week, and each performance will feature a special appearance by a musician. And as expected last night, Grohl stepped offstage to sit in the interviewee chair for a few minutes.

In the first clip, Grohl dives into the premise behind 'Sonic Highways' -- both the new album and HBO series. As Letterman summed it up, "It’s a regional sampling of music in the United States." And we should listen to what Letterman says; Grohl tells the audience, "If it weren’t for these guys and the ‘Letterman’ show, we wouldn’t have been able to make it work."

Following that round of questioning, Letterman dove into the lighter things in life and discussed children with the Foo frontman. Talking about his eight-year-old daughter, Grohl said, “Sometimes her musical taste is a little questionable ... when Violet was young ... she was really into the Amy Winehouse record. It’s an amazing record, but it’s kind of weird to hear a three-year-old sing the ‘Rehab’ song.”

'Sonic Highways' debuts on HBO this Friday, Oct. 17 at 11PM ET. The accompanying album will hit store shelves on Nov. 10 via RCA Records -- get details on the release here.

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