Fred Couples withdrew from the Champion's Tour Boeing Classic on Friday because of back problems on the first hole.
Couples, from Seattle, has a long history of back issues and took three weeks off before the tournament.
After his drive on No. 1 at the TPC Snoqualmie Ridge, Couples lagged behind partners Mark O'Meara and John Cook and rubbed his lower back. When Couples reached his ball, he had a conversation with O'Meara and the two fist pumped. O'Meara and Cook hit their second shots and walked ahead. Couples told his caddie to pick up his ball and the two waited for a cart to return to the clubhouse.
"I didn't feel very good warming up," Couples said. "I hit the tee shot at No. 1 and then my lower back really locked up when I walked down to my second shot.
"It was like a bomb went off in my lower back. I think it's time to rest. I'm sad I won't be able to play in this year's event. For this to happen in Seattle, this is a rough one."
The 1992 Masters champion won the Mississippi Gulf Resort Classic in March and Senior British Open last month.