Australian golfer Jason Day needed medical treatment after dramatically collapsing at the side of the fairway on the final hole of his second round at the US Open.
The Australian hit his tee shot at the par-three ninth into a bunker and then fell to the ground as he made his way down to the green below.
A medical team took several minutes to ensure he was fine to continue before he finished with a bogey four.
He was given more treatment at the side of the green and taken away on a golf cart to sign his card for the round.
The world number 10 is well poised for the weekend, two-under for the tournament and just three shots off the lead.
Day's playing partner, the Masters champion Jordan Spieth, has a share of the lead at 5 under par with fellow American Patrick Reed.
Day's agent Bud Martin issued a statement saying he had been treated on site at Chambers Bay "after feeling dizzy near the end of his round".
"We will provide more information later today after getting through the medical evaluation process. Jason wants to express his appreciation for all the good wishes from so many fans and friends."
Day has been suffering from fatigue and dizzy spells for the better part of a year, withdrawing from last year's World Golf Championship Bridgestone Invitational after a bout and once again having issues in 2015.
He complained of fatigue in the latter part of the Zurich Classic in New Orleans, struggled at the WGC Match Play and the Players Championship and withdrew from the Byron Nelson Championship three weeks ago before it began after struggling with dizzy spells in the Pro-am.
Playing partner Jordan Spieth said that Day had made no mention prior to his fall that he had been felling unwell.
"I was walking with him, the next thing I know I turned around and I think he got dizzy and slipped and fell," the Masters champion said.
Playing in the group directly behind Day's group, Tiger Woods watched on with concern from the elevated tee as one of his close friends suffered.
"I know he didn't play in Dallas this year because of vertigo. And I played with him at Memorial and we talked about it in depth, and he did a blood panel and all that stuff," said Woods who missed the cut.
"I hope he's okay. I'll call him as soon as I'm done here and see if he's all right."
The three-time champion, Woods, carded a six over par 2nd round 76 to miss the cut for just the second time, by a whopping 13 shots.
His 36-hole total - a 16-over 156 is his highest on the PGA Tour as a professional.
Rotorua's Danny Lee, the lone New Zealander in the field, shot a 74 today to exit at 12 over par.