It turns out, Jason Day is human.

The world’s No. 1 golfer has been tearing up the golf world the past two months. Day has won four of his past six tournaments, including the PGA Championship and two of the first three FedEx Cup playoff events. It appeared he was well on his way to leaving the 29 other golfers at East Lake again vying for second place. Day began Thursday’s first round of the Tour Championship with three straight birdies and just missed a fourth.

The round unraveled with one swing.

Day hit his tee shot on No. 5 well to the right. It hit a tree and bounced over a fence. So lost was the ball that the PGA Tour Shotlink labeled its final landing spot as “unknown.”

Day started his own post-round press conference with his own question.

“Everyone want to talk about the shot on 5?” the Australian asked. “Bloody hell.”

Day finished with a triple-bogey 7. He marched on and finished the day tied for 11th at 1-under 69, some six shots behind leader Henrik Stenson.

“It’s one of those swings that got away from me a little bit,” Day said. “Like I’ve said before, I wish I could say that I was a machine and hit it straight down the gut every time 315 yards. But unfortunately, as humans, we are going to make some errors.”

On the fateful hole, Day’s second tee shot landed in the right rough. His approach was short right and again in the rough. He landed on the green 9 feet, 1 inch from the hole and two putts later recorded a seven. It was Day’s first triple-bogey since carding an eight on the 16th hole in the third round of the Bridgestone Invitational in early August.

“Things happen,” Day said. “It’s just unfortunate that it happened that way. I can’t think about it. It’s done and done. You’ve just got to focus on shooting a lower score tomorrow and move on from there. If I can do that, that’s how the best players in the world do it. If I can do that, hopefully I’m close to the lead by Sunday.”

After the ill-fated hole, Day recorded two more birdies, Nos. 8 and 15. He hit another wayward tee shot on No. 16 that lead to another bogey. Day saved par from short of the green on No. 18 – a hole he said he will carry with momentum from into Friday’s second round.

Day entered the Tour Championship as the leader in the FedEx Cup point standings, in the driver’s seat of the playoff title and its $10 million prize. He ended the day projected to finish second behind Stenson.

Day was paired with Jordan Spieth, the reigning Masters and U.S. Open winner who entered the Tour Championship second in the point standings. Spieth finished the first round tied for fifth at 2-under par.

“My club face is struggling at impact right now,” said Spieth, who missed the cut in the first two playoff events. “It’s been something I’ve been trying to get over the past couple of weeks. … But with that struggle, with that being said, I still shot 2-under par.”