Day had two triple-bogeys in the same round for the first time in his career and needed birdie on the par-5 18th to break 80. He was tied for 151st place – five from the bottom. McIlroy was only one shot better.

Day finished a whopping 15 shots behind leader Rickie Fowler. In all, 44 players finished under par — a record for the first round of the US Open. McIlroy made a 30-foot putt for eagle on the short par-4 second hole and was even par at the turn. He shot 42 on the back.

“A little bit of rust,” said the four-time major champion, who was playing for the first time after a six-week layoff he needed to nurse an injured rib. “Timing was a little off. I started missing some left on the course and tried to sort of correct it on the way in and missed a couple right.”

Day’s explanation was more concise: “I just played bad golf, man. I can’t put it any other way.”

He never saw it coming.

Day said he had the best preparation he’s ever had heading into a major – even better than 22 months ago when, 70 miles away at Whistling Straits, where he won the PGA Championship for his first major. Erin Hills must have felt like another planet, not the same state.

Day’s meltdown began when not one, but two chips from the first cut of rough behind the fourth green hit the top of the hill, then trundled back down to almost where Day was standing. He made sure the third chip went well past the flag, but triple-bogey seven was the best he could do.

It wasn’t the only one.

His tee shot on No 10 landed in the deep fescue, and the second shot barely moved. He punched the third back into the fairway but needed two more to get on the green and two to get down for his second seven.

“It’s weird,” he said. “Because it’s not like I gave up.”

Nor did McIlroy, though it must have been tempting.

On a day in which 105 players hit 10 or more fairways, McIlroy only hit five. He was holding his own until the fescue ate him up on 15, then on 17, when he hit into the tall grass on the side of a steep hill and had to hit the next shot with the ball so far above his feet, he couldn’t tell where it was going to go. He made double-bogeys on both holes to balloon to six-over.

“There are a lot of things I could have done better today, obviously,” McIlroy said. “Just have to try to go out tomorrow and rectify those.”

Day’s 79 came despite making birdies on all four par-5s. After his round was over, he cut a lonely figure on the end of the driving range, trying to work out the kinks and stay positive.

He’ll need so much help, and he figures it might need to start with the USGA.

“I’m assuming the USGA obviously doesn’t like to see seven-under lead their championship at the start of the tournament,” Day said, referring to Fowler’s 65. “So if I get through to the weekend, I can slowly inch my way back.”

Getting to the weekend might feel like a victory all by itself.

“There’s nothing I can hide behind,” Day said. “Just have to go out and focus harder and try to get it done.”