CHASKA, Minn. — Paul Casey, who has been battling a rib injury for the last month, says he will decide Thursday morning whether or not to try to play in the 91st PGA Championship at Hazeltine National Golf Club.Casey is scheduled to go off at 8:45 a.m. Eastern Thursday; if he can't go, he would be replaced by fifth alternate Tim Petrovic. The winner of three early-season tournaments in 2009, including the PGA Tour's Shell Houston Open in a playoff, Casey moved to No. 3 in the World Ranking. But his year in the majors has been forgettable. He finished T20 at the Masters and missed the cut at the U.S. Open before hurting himself while hitting a shot in preparation for the British Open at Turnberry last month. He played through it and finished T47.After taking time off to heal, Casey aggravated the injury while trying to hit out of the rough at last week's WGC-Bridgestone Invitational in Akron, Ohio, and withdrew after six holes."There's really nothing much you can do for it except rest," he said after getting treatment for the second time Wednesday. He had not played a single hole of a practice round, but at least he knows the course. He played the 2002 PGA here (85-74), missing the cut, and the 1999 NCAA Championship, where he finished 4th, six shots behind winner Luke Donald. Casey spent some time Wednesday afternoon going over the signatures on the field list that week, which is framed and hangs just outside the locker room.Lucas Glover played that week, as did several others in the field for this PGA."We had some really good players in that era," Casey said.