Bryson DeChambeau delivered a credibility boost to LIV Golf, firing a four-under par 66 to seize a one-stroke clubhouse lead in Thursday's darkness-halted opening round of the PGA Championship.

The slimmed-down 2020 US Open champion, coming off 2022 left wrist surgery, struck a competitor with an errant shot but the 29-year-old American managed six birdies against two bogeys to top those who finished 18 holes at formidable Oak Hill.

There were 30 players still on the course when play was halted, the finish delayed after Thursday's round started one hour and 50 minutes late due to frost

Among those yet to finish was US PGA Tour rookie Eric Cole, who was ahead on the course at 5-under through 14 holes, making six birdies against a lone bogey

"I played solid for the most part and got a couple of good breaks when I needed them," said Cole, son of 25-year LPGA veteran Laura Baugh and South African Bobby Cole, who was third at the 1974 PGA Championship. "It was a good day."

DeChambeau said the same.

"I hit my putts really well and drove it nicely," DeChambeau said. "I faced some tough challenges and was able to execute the way I wanted to and, man, it feels really good."

DeChambeau sent his approach at 17 into the 18th tee box, striking rival player Kenny Pigman in the right arm but not hurting him.

DeChambeau was among the PGA Tour players who jumped to Saudi-backed LIV Golf, which offered record $25 million purses and 54-hole events some said would ruin players for major competition.

DeChambeau's effort and Masters runner-up efforts by Brooks Koepka and Phil Mickelson have proven LIV talent can compete for major titles.

"It's just where we play at. It doesn't change the style of golfer we are," says two-time major winner Dustin Johnson, who opened on 67.

The PGA Tour banned LIV players and their legal fight is set for trial in a year. In the meantime the majors are the only place where the best of both tours can compete.

World number two Scottie Scheffler, fellow American Johnson of LIV and Canada's Corey Conners shared second in the clubhouse on 67.

"It was a grind. The golf course was very tough," Scheffler said. "And I think these will be the easiest conditions we have all week."

New Zealand's Ryan Fox, 2011 PGA Championship winner Keegan Bradley, Norway's Viktor Hovland and 2013 Masters winner Adam Scott of Australia were on 68.

DeChambeau, once bulked up to boost his power driving, has trimmed down to ease inflammation in his body and says he has the form to win another major.

"(I learned) I can do it again," he said. "I've got a lot more years for my career.

As for this week, "I don't know if I can hold it for four rounds but I played pretty well."

Scheffler, this year's Players Championship winner and last year's Masters champion, had a bogey-free round.

"I scrambled for 3-under," Scheffler said. "I was proud getting around here with no bogeys, which is really tough."

Conners had runs of three birdies in four holes on both the front and back nines.

"Felt good to see some putts go in," Conners said

Four-time major winner Rory McIlroy, seeking his first major triumph since 2014, landed in only two of 14 fairways in struggling to a 71.

"Didn't hit the ball well at all," McIlroy said. "Thought I did really well to shoot one-under in the end.

"I'm going to have to play a lot better if I want a future in this tournament."

Defending champion Justin Thomas opened on 72 along with British Open champion Cameron Smith of Australia and his fellow LIV Golf star Koepka.

World number one Jon Rahm, the reigning Masters champion, started with a birdie at the 10th hole and added another at the eighth but in between had six bogeys and a double bogey to finish on 76.

"Couldn't find the fairway and the fairways that I missed cost me bogeys," Rahm said.

Reigning US Open champion Matthew Fitzpatrick of England had six bogeys to join Rahm on 76.