The 12-song set -- tentatively titled "Echoes, Silence, Patience and Grace" and due September 25 via RCA -- set may throw some fans for a loop. Tracks like "Let It Die" and "Erase Replace" make drastic stylistic shifts in a matter of seconds. "There's four-piece rock band s--t, but then there are songs where the middle sections turn into this mass orchestrated swarm and ridiculous time signatures," Grohl said of the new material.

Among the rockers sure to sizzle in arenas this fall are opener "The Pretender" ("It's a stomping Foo Fighters uptempo song, with a little bit of Chuck Berry in it") and "Cheer Up Boys, Your Makeup Is Running" ("That will make festival grounds stomp really hard").

At the other end of the spectrum, "The Ballad of the Beaconsfield Miners" finds Grohl and guest guitarist Kaki King flexing their fingerpicking. "This song is almost banjo-picking style with hammer-ons and pull-offs," Grohl said. "I showed it to her once and she shredded it 10 times better than I've ever played it." That song was inspired by two Tasmanian miners who were trapped underground for two weeks and, while awaiting rescue, requested an iPod with Foo Fighters music on it to help lift their spirits. Grohl was alerted of the situation by a staffer at the band's Australian record company and wrote a note to the two men. "I was in tears, man," he recalled. "I said, 'Hey guys, it's Dave. You're in our thoughts and prayers. When you get out, there's two tickets and two cold beers waiting for you wherever you want to see the band."' The men were eventually brought to safety, and when one of them came to see the Foos play at the Sydney Opera House, "I thought I'd write something for him," Grohl said. "I came up with this little instrumental thing. After the show, we went and got f---in' wasted in the hotel bar and I was like, 'Dude, I promise I'm going to put this on the record."' After some one-off shows this summer, the Foos will play U.S. gigs in September and October, followed by U.K. arenas in November and Australian arenas in December. Another U.S. run is on tap for early spring. "The last American tour we did was the one with Weezer (in 2005)," Grohl said. "We need to get back to Fargo and Tulsa -- places like that. We need to bring it all back."