PITTSFORD, N.Y. — Bryson DeChambeau was back on a major stage Thursday. No longer the incredible bulk, he still lashed away with speed and strength that carried him to a 4-under 66 at tough Oak Hill and the early lead in the PGA Championship.

DeChambeau kept the ball in play for most of the round and powered his way out of the gnarly rough the few times he got out of position. He matched his low score at the PGA Championship and led by one over Scottie Scheffler, Dustin Johnson and Corey Conners.

Still to be determined was whether he would be leading after the opening round. A two-hour frost delay meant 30 players didn’t finish because of darkness. They were to return Friday morning to finish. That included Eric Cole, the 34-year-old PGA Tour rookie who was at 5 under with four holes remaining.

“It’s a fantastic round of golf at Oak Hill,” DeChambeau said. “It’s a prestigious place, very difficult golf course. As I was looking at it throughout the week, I’m like, ‘Man, I don’t know how shooting under par is even possible out here on some of the holes.’ But luckily, I was able to play some really good golf.”

So did Johnson, the two-time major champion who is coming off a playoff win last week in Oklahoma in the Saudi-funded LIV Golf League. Johnson went from a fairway bunker to deep rough left of the 18th green and missed a putt just inside 15 feet for his only bogey.

“I didn’t have my best stuff, but I felt like he managed the golf course very well and took advantage of the opportunities when I had it,” Johnson said. “Made some crucial saves there on the back side.”

Fairways covered with a thin layer of frost gave way to magnificent weather with little wind.

“Today was probably the easiest conditions we’ll see all week,” said Scheffler, who took advantage with his first bogey-free card in 51 rounds at a major.

Masters champion Jon Rahm failed to take advantage, making five bogeys in a six-hole stretch around the turn and finishing with a 76, his highest start at a major since the 2018 U.S. Open. Jason Day, coming off a win at the AT&T Byron Nelson, and U.S. Open champion Matt Fitzpatrick also were at 76.

Scheffler challenging for the lead was not a surprise. Last year’s Masters champion has six wins in the last 15 months, and he hasn’t finished worse than 12th this year. Johnson had a slow start to the year but is starting to hit his stride. He won the LIV points list last year.

As for DeChambeau, he practically vanished from golf’s elite over the last year.

He injured his hip in early 2022, attributing it to slipping on marble tile playing ping-pong in Saudi Arabia. He had surgery on his left wrist after the Masters last year. And then he joined the Saudi-funded LIV Golf League, where his tie for fifth last week in Oklahoma was his only top-10 in six events this year.

“The emotions have definitely fluctuated pretty high and pretty low, thinking I have something and it fails and going back and forth. It’s humbling,” DeChambeau said. “Golf, and life, always has a good way to kicking you on your you-know-what when you’re on your high horse.

“It’s nice to feel this today.”

His only big miss came on his approach to the 17th out of rough. It sailed to the right toward the 18th tee and plunked club pro Kenny Pigman, who shook it off and then shook hands with an apologetic DeChambeau.

This isn’t so much a transformation as a restoration. His goal is no longer to create a new way to approach the game, rather to find what brought him success when he won eight times in a span of three years, including a U.S. Open title at Winged Foot.

Gone are the days when he consumed some 5,000 calories a day in a bid to build a body — he was called the “Incredible Bulk” — that could tolerate him swinging as hard as he could to overpower golf courses.

He began a diet that reduces inflammation (he estimates his daily calorie intake at 2,900) and tried to find his way back to 2018, when he felt he was at his best.

“I want to be just stable now,” he said. “I’m tired of changing, trying different things. Yeah, could I hit it a little further, could I try and get a little stronger? Sure. But I’m not going to go full force.

“It was a fun experiment,” he said, “but definitely want to play some good golf now.”

Scheffler has been doing that all year, and the opening round of the PGA Championship was no exception. He made a stressful golf course look stress-free, except for a few holes.

One of them was the second hole, his 11th of the round, when he went over the green and faced a scary chip up a steep slope to a back pin. He pitched up to 7 feet and saved par. He also got out of position on the par-5 fifth hole, getting up and down from a bunker for par.

“It was a grind today,” Scheffler said. “No bogeys is pretty solid.”

For so many others, Oak Hill was the grind they expected. Jordan Spieth felt fit enough with an injured left wrist to pursue the final leg of the career Grand Slam, only to struggle with his putting. He shot a 73.

Rory McIlroy looked as though he might be headed to another early exit from a big event. He was 3 over after nine holes and in trouble at No. 2 when he was over the green in three, some 35 feet away with a steep slope between him and a back pin.

He holed it with his putter for a most unlikely par, made birdie on the next two holes and salvaged a 71.

“It was massive,” McIlroy said. “Depending on what happens over the next three days and what I go on to do, I may look back at that shot as being the sort of turning point of the week.”

Rahm had a long road back. He was 1 under and right in the mix until he started missing fairways, into the rough and deep bunkers, and dropped out of sight. Defending champion Justin Thomas and Masters runner-up Brooks Koepka were among those at 72.

The forecast was for warmer weather and a little more wind. The forecast for the PGA Championship also includes DeChambeau.

“Golf is a weird animal. You can never fully have it,” DeChambeau said. “You always think you have it one day and then it just leaves the next. Just got to be careful.”