Greenwood also scheduled to sing anthem

AIR FORCE ACADEMY, Colo. -- Grammy Award-winning singer Lee Greenwood will not perform during the Air Force-Navy football game Thursday because of an illness, the academy announced Wednesday.

Greenwood was scheduled to perform his 1983 hit song "God Bless the U.S.A" during halftime and sing the national anthem before the game.

"He can hardly speak. He's got some kind of a flu bug," publicist Kirt Webster said Tuesday.

The academy said the illness prevents Greenwood from flying.

The singer-songwriter won a Grammy for best male country performance in 1983.