World No 17 Patrick Reed confirmed on Monday that he is hospitalised in Houston with bilateral interstitial pneumonia.
The illness will keep him out of the BMW Championship, which begins Thursday in Maryland.
The 31-year-old Reed had a rough weekend, according to a statement by his wife, Justine.
“Patrick is still in the hospital but he’s doing much better,” she said. “It was very scary the last few days, and right now we don’t have a timeline on his recovery.
“I never count him out but I do know he will not be able to play BMW. We are just taking it one day at a time. We are following all of the doctors orders and you can sure bet as soon as they give him the go-ahead to play, he will.
“But our main concern now is just getting him back 100 per cent.”
Reed withdrew from the Northern Trust due to an injured left ankle.
According to the Golf Channel, Reed was diagnosed with the illness – often referred to as double pneumonia – while having his ankle examined on Wednesday. The illness causes infections in both lungs.
Reed was admitted to Houston Methodist Hospital on Friday morning, according to reports.
Reed said he can feel improvement in his condition.
“I’m on the road to recovery,” Reed said in the statement. “Once I’m cleared from the doctors, I look forward to returning. I wish you all the best and I can’t wait to get back out there.”
Reed entered the Northern Trust at No 22 in the FedEx Cup playoff standings and ninth in the Ryder Cup standings.
Missing the BMW Championship would prevent Reed from earning top-six automatic status for the US Ryder Cup team but captain Steve Stricker could use a captain’s pick on him for the competition at Whistling Straits in Wisconsin from September 24th-26th.