Louis Oosthuizen limped out of the Tour Championship on Thursday after suffering a hamstring injury during the first round, placing a question mark against his fitness for next month`s President`s Cup.
Oosthuizen withdrew after 13 holes at East Lake Golf Club after sustaining a muscle strain earlier in the round. The 2010 British Open champion was five-over-par when he pulled out.
The 32-year-old later revealed the injury had impeded his ability to swing properly.
"It was getting worse and once it gets to a point where you don`t swing it proper, it`s no point in playing," Oosthuizen said.
"That`s when you start losing confidence and you start hurting other things."
Oosthuizen said he still hoped to play in the Dunhill Links next week but admitted his participation was in jeopardy.
"I still would love to play next week, Dunhill Links, that`s a big concern now, because that`s also a tough walk, those three golf courses."
The South African said he planned to return to Florida for intensive rehabilitation.
"My physio is actually going with me down to Palm Beach and we`ll do some work on it," he said.
"Probably can`t do much at the moment, it`s quite tender, but I think that the next couple of days, we`ll do some proper work."
Oosthuizen said he planned to inform President`s Cup skipper Nick Price next week whether he would be fit to play in the October 7-11 event in South Korea.
"It`s not just the individual thing, the Presidents Cup, it`s a team thing, so I need to make a call on next Wednesday or Thursday and tell Nick Price if I`ll be a hundred percent or not."