Last night, Foo Fighters kicked off their week-long residency on The Late Show with David Letterman. The band got things off to a running start, inviting country guitar guru Zac Brown to join them for a version the Black Sabbath classic “War Pigs”. This is not Brown and The Foo’s first collaboration, however. Foo Fighters frontman Dave Grohl joined forces with the Zac Brown Band last year for The Grohl Sessions, Vol. 1. Zac Brown Band and Grohl performed together last November at the 47th Annual CMA Awards. Last night, it was Brown’s turn to join Grohl’s band for a jam. Foo Fighters are set to release their much-anticipated new album Sonic Highways on November 28 10 via RCA Records. The series premieres on October 17 at 11PM EST on HBO. Foo Fighters are set to headline Life Is Beautiful Festival in Las Vegas on October 26 and Voodoo Experience in New Orleans on October 31. In 2015, the band will embark on a tour kicks off on January 15 in Santiago, Chile and wraps up on January 31 in Bogotá, Colombia. – by Matt Bishop