Brooks Koepka said he is "heartbroken" after it emerged that a spectator struck in the eye by one of his tee shots during last week's Ryder Cup could lose sight in her eye.
Corine Remande was smacked by a wayward shot on the par-four sixth hole at Le Golf National in Paris.
Doctors say she suffered the fracture of the right eye-socket and an explosion of the eyeball.
Koepka said in a statement on Twitter that he was "deeply hurt and saddened" by what he described as a "tragic accident"
He said: "Yesterday was probably one of the worst days of my life," Koepka said. "I haven't had too many tragedies in my personal family where there's been a loss or any kind of tragic accident so I've been lucky in that sense.
"I wasn't told until I got to the course - I'm not the biggest person on social media - so when I got here and had about seven missed calls and 25 text messages I was like, 'What's going on? Then I was told the news and obviously I am really heartbroken.
"My stomach sank. Yesterday was probably one of the hardest days trying to focus and play golf just knowing what was going to come when I was done.
"I spent an hour-and-a-half of my round on the phone trying to understand what was going on because it's hard to get the real story of what was going on. I didn't know if it was fake or not and you want to find out. It's sad and I really am torn up about it."
The American also addressed reports of a heated row with his friend and Ryder Cup team mate Dustin Johnson.
Tabloid reports suggest the argument centered on Koepka's relationship with Johnson's girlfriend occured in Europe's Team room late on Sunday evening.
Two weeks ago, Paulina Gretzky deleted all pictures of Johnson from her Instagram page which prompted reports of strain in their personal relationship.
"This Dustin thing I don't get," Koepka said at a press conference ahead of his appearance in the Alfred Dunhill Links Championship. "There was no fight, no argument.
"He's one of my best friends. I love the kid to death. We talked on the phone Monday and yesterday so you tell me how we fought. People like to make a story and run with it. It's not the first time there's been a news story that isn't true that's gone out."
"As far as camaraderie, it was fine, it was perfect," Koepka added. "The problem is you guys try to find a reason why we lost and the simple reason is we just didn't play good enough.
"We didn't make the putts, hit the fairways, especially me. I lost two matches and halved another one. If I won those, if Tiger wins his; Dustin lost one with me and then I think lost in the singles.
"If we play how we're supposed to play we win, it's simple as, but there's nothing wrong with our team. Our team was great, Jim was great."