Fred Couples has withdrawn from the U.S. Senior Open because of a back injury.
Couples, 55, has a long history of back trouble. He missed the cut at the Masters and has not played in two months. Couples also pulled out of qualifying earlier this month for the U.S. Open, held outside his hometown of Seattle.
He was runner-up at the U.S. Senior Open in his first year of eligibility and has not recorded a top 10 in the event since then.
Couples, who was replaced by Paul Trittler of Cave Creek, Ariz., is the latest player to withdraw from the event.