Ozzy Osbourne missed out on his namesake tour Wednesday after being diagnosed with severe laryngitis.
Korn slipped into the headliner spot for the Maysville, California, show so Osbourne could take a breather, and refunds are being offered to fans who had come to see Ozzy.
"After struggling through his performance in San Francisco [Tuesday], Ozzy Osbourne was examined by his personal physician this morning and was diagnosed with having severe laryngitis," a tour spokesperson said in a statement. "Ozzy's doctor has ordered him to rest his vocal cords for the next few days."
The statement said Ozzy's doctors are confident his condition will improve with a few days' rest and that he should be in shape to rejoin the festival on Saturday in Seattle.
One Osbourne who hasn't lost her voice is eldest daughter Aimee. She has stayed out of camera range during the family's run on "The Osbournes," but the aspiring singer will soon be seen on MTV as Raquelle in an updated musical adaptation of the Emily Brontë romance classic "Wuthering Heights." The movie, due September 4, also features Erika Christensen ("Swimfan"), Katherine Heigl ("Valentine") and Christopher Masterson ("Malcolm in the Middle").