Jason Day collapsed on his final hole of the day in the second round of the U.S. Open, falling to his knees on the fairway as he walked toward a greenside bunker where his tee shot had landed.
The world number 10 was one under for his round and in contention at three under for the tournament as he approached the ninth hole - his last of the day.
However, Day - who underwent tests prior to this week's event after struggling with vertigo - then slumped to the floor as he walked up the ninth fairway, with medics quickly arriving on the scene to attend to the Australian.
After a short delay, Day completed his round with a closing bogey, although he continued to look unsteady on his feet and crouched down on one knee after holing out.
At the end of his round it was unclear whether he would continue in the tournament.
According to reports, he later told Greg Norman he plans to return for the third round tomorrow.
"All I heard was that it was dizziness," explained playing partner Jordan Spieth to Fox Sports.
"To finish the round was pretty strong. I've played a lot of golf with Jason but I didn't notice much.
"First and foremost it's good that he was healthy, me and Justin [Rose] just told him to get some rest, some water, but other than that there was nothing different."