Defending champ Casey pulls out of Houston Open

Defending champion Paul Casey has withdrawn from the Houston Open because of a left shoulder injury.

Casey said Thursday that his shoulder feels "pinched" and is restricting his backswing. He says one of his rib muscles is also tight, but it's unrelated to the rib injury that limited him to two European Tour events over the last five months of 2009.

The 32-year-old Englishman is hoping the latest injury is "just a one-week thing" and won't keep him out of next week's Masters.

"I'm visibly disappointed not to be going out there and playing today," Casey said. "But I've got to worry about the rest of the season and after last year's experience, trying to play through an injury, I tried to do that for two weeks and it ended up costing me six months. The last thing I can afford to do is try and push it and cost myself any more time."

Casey has four top-10 finishes in four PGA Tour starts this year. He tied for fourth at the Honda Classic at Palm Beach, Florida, and tied for sixth at the CA Championship at Doral, Florida.

He defeated J.B. Holmes in a playoff in Houston last year, his first and only PGA Tour victory. Casey said he probably won't hit balls for 2-3 days and will stay in Houston to get treatment on his shoulder.

"We'll keep looking at it and keep taking care of it," Casey said. "Unfortunately, that's what I have to do."