Patrick Reed has won 12 events during his career on the PGA Tour and European Tours.
Patrick Reed said he was "in a dark place" and "fighting for his life" after he was warned that his bout with double pneumonia could be fatal.
The condition was brought on by the American in Houston, Texas.
"I believe I was there for five to six days. The 2018 Masters champion said, "I don't know how long."
"I can't recall the exact time I was in the hospital, but it felt as if it took forever."
After shooting a two over-par 72 in round one of the Tour Championship, the 31 year-old said: "The first few days, they were sitting right there telling me to text my family quite a lot, talk with your family, because you just do not know.
"This is not good. "We're not in a favorable spot right now.
"With the way hospitals are now because of Covid they won't let people in there so you're the only one allowed in there.
"So, I'm sitting here and these first two days, I only thought that I wouldn't be able tell my children goodbye. I won't be able tell them that I love them. I won't be able tell my wife I love her or give her a hug.
It definitely puts you in a dark place, especially the first two days. It was a difficult time, but I am so grateful to have such an amazing team of doctors and amazing people who helped me get through it.
"And to think I'm able be here and to play, I felt OK. Although it was frustrating not being in a position to make the shots or feel certain emotions, I took a lot of time off.
"It was like I was fighting for my life. The good news is that I am now able to hit the ground running, hopefully."
Reed, who was absent from the FedEx Cup playoff events, said that he was only playing this weekend to impress Steve Stricker, the United States Ryder Cup captain. He will make his six wildcard selections on Sunday in the match against Europe at Whistling Strits, 24-26 September.
Reed said, "The most important thing is to make sure I'm well and just to be able see where I am at." Reed has already won eight points in his three previous Ryder Cup appearances.
"And I know that the Ryder Cup will be there to help me improve my game - so long as my health is good and I feel like I can continue to play golf."