World number one Rory McIlroy has cast further doubt on whether he will be able to play in August's US PGA Championship at Whistling Straits by pulling out of next week's WGC-Bridgestone Invitational.
The Northern Irishman was forced to miss this month's Open Championship after rupturing his ankle ligaments shortly before the event, and his camp admitted that they were unsure of when he would be fit to return.
The 26-year-old, who is the reigning champion at both Bridgestone and the US PGA, said in a statement: "Unfortunately, I will not be defending my World Golf Championships-Bridgestone Invitational title. Best of luck to all the competitors and I look forward to returning to Firestone [Country Club] in 2016."
McIlroy has been world number one since winning last year's Bridgestone and US PGA Championships, but medical experts have warned that he could be facing around three months out with his injury.
