UNIVERSITY PLACE, Wash. -- Australian Jason Day, in contention at the U.S. Open, fell to the ground while playing the ninth hole Friday, his final hole of the second round at Chambers Bay, and later was diagnosed with vertigo.
Day, ranked 10th in the world, at first appeared to slip, but television replays later showed he simply went to the ground as if he had fainted. There is a big slope in front of the grandstand on No. 9, which is where he fell.
"Jason was diagnosed to have suffered from Benign Positional Vertigo," Day's agent, Bud Martin, said in a statement released by the United States Golf Association on Friday night. "He was treated locally by Dr. Robert Stoecker and Dr. Charles Souliere and is resting comfortably. His condition is being monitored closely and he is hopeful he will be able to compete this weekend in the final rounds of the U.S. Open. He wants to thank all who treated him at the Franciscan Medical Group and thank all of the fans and friends who have reached out to he and his family."
Medical personnel attended to Day for several minutes after he collapsed, and it took him some time before he could get up. At times, he used his club as a crutch.
Photographers started to take pictures when Day collapsed, and Spieth, his playing partner, waved them off. When Day sat up, Spieth kept playing bodyguard with the photographers.
"I turned around, and he was just laying there," Spieth said.
Day was later treated at the Franciscan Medical Group in Burien, Washington. Vertigo is a sensation of spinning.
Day withdrew from the AT&T Byron Nelson after feeling dizzy three weeks ago. He underwent multiple tests, but nothing was conclusive. Day addressed how he was feeling earlier this week during a news conference at the U.S. Open.
Jason Day, from earlier this week: pic.twitter.com/4t49B2UaGa— Jason Sobel (@JasonSobelESPN) June 19, 2015
Day's tee shot at the par-3 ninth hole had gone into a greenside bunker, and Day managed to play his shot onto the green. His playing partners, Rose and Spieth, let him putt first as it was clear Day was still not feeling well.
Day two-putted for a bogey to shoot even-par 70 and complete 36 holes at 138, 2 under par. He slowly made it to the side of the green afterward to seek more medical attention and then hopped on a cart for a drive to the scorer's trailer to sign his scorecard.
His caddie, Colin Swatton, said this was similar to an episode Day had at last year's World Golf Championship event at Firestone in Ohio; Day had completed two holes that Sunday when he had to withdraw because of dizziness that was later diagnosed as vertigo.
Day's wife, Ellie, who is pregnant with their second child, was at the course Friday.
"He gave me a heart attack there for a minute," she said. "I think it's encouraging that he wanted to finish. He's like, 'I don't care, I'm dizzy, but I'm just going to finish.'
"I just asked him if it just happened, and he said it just happened. I've never seen it come out of nowhere like that. I mean, I saw him have it in Akron last year really bad because we were on the bus and he was like, 'What is going on?' He was like, 'I swear the bus is moving right now,' and I'm like, 'It's definitely not moving.' And it was really bad then, but they did those maneuvers and it seemed to help."
Day left the trailer Friday with assistance and then was taken away in a van. He later was shown on the TV broadcast entering a motor home on the course.
"I was glad we could get done," Rose said. "At least he has a chance to recover for tomorrow, hopefully. I don't know if this is one of those things that is 10 minutes or a day. I don't know."
Information from ESPN The Magazine's Chris Jones, ESPN.com's Ian O'Connor and The Associated Press was used in this report.