World number three Paul Casey tested his strained rib muscle on the Hazeltine practice range on Tuesday and will play a practice round on Wednesday before deciding about playing in the PGA Championship.

The 31-year-old Englishman withdrew after six holes from last week's World Golf Championships Bridgestone Invitational after straining an intercostal muscle that he first hurt last month while preparing for the British Open.

Casey spent the past few days at the WGC tournament site in Akron, Ohio, receiving treatment and icing the injury before coming to the venue for the year's final major tournament to see if he might be fit enough to compete.

"It's a frustrating injury to receive as the only real cure is rest," Casey said. "I will hope this improves so I can initially participate in the PGA Championship.

"I will hope that any layoff is as short as possible."

Casey aggravated the injury 3 August during a practice round at Firestone Country Club in Akron while playing a shot out of the rough.

Casey, who trails only Tiger Woods and Phil Mickelson in the world rankings, won titles this year at the Abu Dhabi Championship and the BMW PGA Championship on the European PGA Tour as well as the US PGA Houston Open.