For the first time in the history of Summerfest, the American Family Insurance Amphitheater will be empty and without a headliner. On July 4th this year there will be no main stage headliner. Originally Ozzy Osbourne was scheduled to play the big gig that night but he had to cancel his tour due to illness. Ozzy was replaced with Megadeth and other bands on July 4th. It was announced via twitter that Megadeth frontman Dave Mustaine has been diagnosed with throat cancer. With the news of Mustaine's cancer and the tour being cancelled, Summerfest has announced there will not be a headliner on July 4th. Summerfest is claiming that with the festival starting in less than two weeks they will not be pursuing a band for replacement.