Foo Fighters [ tickets ] won't be taking the stage at Morrison, CO's Red Rocks Amphitheater tonight and tomorrow night as originally planned.

The group has pushed both shows back until September while band frontman Dave Grohl recovers from an unspecified illness.

"As much as it kills us to postpone shows, I'm in no shape to deliver the kind of balls-out performances that you guys deserve," Grohl said in a prepared statement. "We're already looking forward to September when we can make it up to everyone 10 times over. It's gonna be great."

Tickets for the July 14 show will now be valid for a Sept. 8 make-up date, and those for the July 15 show will be honored Sept. 9, according to a press release. Refunds are also available at the point of purchase.

The group's tour is scheduled to resume Thursday (7/17) in Oklahoma City.