Bryson DeChambeau closes out an excellent round with a measured par on the ninth hole.

He's made six birdies today and this is the best Bryson we've seen in some time.

Former champion Keegan Bradley has had a fine round but ends with a disappointing bogey.

He'll start the second round two behind his compatriot.

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Four-time major winner Brooks Koepka finished in a tie for second at the Masters but isn't happy with his first round effort at Oak Hill: "That was the worst I've hit it in a long time. Scrambled really well. Missed a couple putts early but scrambled really well late. Yeah, that was the worst I've hit it in a really long time.

"I doubt it's going to happen tomorrow, so [I'll] just go figure it out and see where it puts me."

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More from Rory McIlroy, who is asked about a conversation with Justin Thomas that the TV microphones picked up on the 10th tee:

"I'm fighting something. I thought I got a great night's sleep last night, and I look at my Whip, and I was 22% recovery, and my skin temperature was 3.5 degrees higher than what it's been.

"I'm fighting something. But I actually feel better today than I felt yesterday, so plenty of water and a bit of rest, I'll be fine."

On the course conditions: "I don't know what the conditions are going to be like over the next few days. It was certainly benign out there.

"I think what happened this morning as well, as the frost thawed, it made the golf course a little softer than it had been over the last couple of days. The aprons weren't quite as fiery as they were Tuesday/Wednesday. If the place firms up a little built again, I could definitely see this being the easiest day."

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Rory McIlroy battled away earlier on to get into the clubhouse with a one-over par 71. And from the sounds of it the four-time major championship winner reckons there's a lot of room for improvement.

Asked about only hitting two fairways and generally having to tough it out he said: " [I was] Just not at my best. I'm just struggling with my swing.

"Yeah, it's pretty messy out there, so just trying to make pars. I guess it was tough as well. There was a lot of crosswinds off tees, so it made it hard to hit fairways. Yeah, I know, I can definitely hit it better than that.

"I guess, if anything, I started to see a couple of better golf shots coming down the last few holes. Hit that good 6-iron into the third hole and two great shots into four. Good iron shot into six. Nice wedge shot into eight. There were a couple of glimmers of hope in there coming in."

Having taken five shots to get on the green on the par-four second, Xander Schauffele sinks a short putt for a double bogey.

Still a possible 70 holes to go, of course, but the American has given himself an incredibly uphill task.

As has Tyrrell Hatton, who also records a double bogey. There hadn't been a bogey on the second hole - the shortest par-four on the course - until this group played it. Ouch.

A beautiful tee shot from Adam Scott gets him in close on the par-three third. Poised in his upright stance, he holes a composed putt to move into the red.

That's only the eighth birdie on this hole today.

Despite missing the green, Tony Finau is a picture of cool in his yellow cap and matching polo shirt and he chips to within tap-in range and slots it in to save par.

Max Homa has the best par-three scoring average on the PGA Tour this year but he’s found the lip of the green and his ball is still rolling backwards. It all ends upw with two bogeys in the opening three holes for the American.

A pair of the pars for the leaders who were both off target from the tee but find different ways to save themselves..

Faced with lengthy putts, there's good control on display and both Bryson DeChambeau and Keegan Bradley advance to their final hole of the first round with their scorecards in the same condition.

Not sure Xander Schauffele will have played two worse holes in his life than the opening two here.

After that opening bogey five - which he was arguably lucky not to double - the American over-pitches from the rough by the literal country mile.

The ball flies past the flag, down the slope and off the other side, into more rough.

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Phil Mickelson receives arguably the biggest cheer of the day on the first tee. The shock 2021 US PGA champion carves his opener right, into the thick stuff.

Rickie Fowler is also out that way, while the third member of the group, Patrick Cantlay, finds a bunker.

Lefty thrashes his second into the guts of the green and two putts from there for a solid opening par.

Fowler, who I think every right-thinking golf fan would like to see win a major, is a little long with his second and then a touch wayward with his third. A 12-foot par putt does a 360 round the hole and stays up.

Cantlay gets up and down from the front edge to salvage par.

Xander Schauffele's third shot wasn't much better than his wild opening two as a little chip from the edge of the green barely gets halfway to the hole.

A 25-footer for par goes wide and he signs for a bogey to open, as does Tyrrell Hatton.

Former Masters and US Open champion Dustin Johnson begins his bid for a third major with a par.

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Well, well, Bryson DeChambeau has himself the solo lead with two holes to go in his opening round.

It's not a pretty par save but it's effective. Wide left from his second shot, the American chips from the rough to 12 feet and sinks a nerveless putt.

Perhaps he was helped by Keegan Bradley who missed a par putt of his own just seconds earlier to slip back a shot.

DeChambeau did not really feature in the conversation before this championship.

We're talking about him now.

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The majors are of course the only place where the PGA Tour and LIV players can compete against each other at present.

And Dustin Johnson says those now on the Saudi-backed tour have nothing to prove at this week's PGA Championship and that was true before three LIV players finished in the top six at the Masters.

Two-time major champion Johnson is among 16 LIV players from the Saudi-financed breakaway series who will compete this week at Oak Hill, six of them past major winners.

"I would hope at some point we can all co-exist and work together," Johnson said.

"That would be nice. I've proven myself out here for a long enough time where to me I don't need to keep proving myself.

"I already have for many years. Same with all the other guys. Where we play at, it doesn't change the style of golfer we are."

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A slap of the thigh in frustration for Cam Smith as he watches his eight-foot par putt on the ninth, his last of the day, sidle past the right edge of the hole. A disappointing finish for the Australian.

Jon Rahm has again gone rough, rough with his opening two shots. His third shuffles up to within five feet of the hole. Big par putt coming up... birdie-par finish so much better than birdie-bogey... par it is.

And Matt Fitzpatrick is also in for a final par. Three bogeys on each nine and a birdie-free round though for the US Open champion.

Here's how the top of the leaderboard looks with some of those early marquee groups now tucked up in the clubhouse.

-4 Bradley, DeChambeau

-3 Scheffler (F), Conners (F)

-2 Fox (F), Hovland (F), Buckley, Straka

Selected others:

E Tarren,

+1 McIlroy (F), Morikawa (F)

+2 Koepka (F), Thomas, Smith

+3 Lowry (F), Spieth (F)

+6 Rahm, Fitzpatrick

One of our evening marquee groups is under way, Englishman Tyrrell Hatton flanked by American duo Dustin Johnson and typist's nightmare Xander Schauffele.

Schauffele's tee shot at the first barely evades the paying spectators and his second flies over the back of the green. Not the best start.

The popular Tony Finau is much fancied to win his first major this week and he's off to a steady start on the first hole with an even par.

Australia's Adam Scott joins him but Max Homa hit his third in the bunker and could not get up and down to rescue a par.

On his 15th major championship start, world number two Scottie Scheffler records his first bogey-free round in a major with a three-under 67.

Scheffler has two top-10s in three previous starts at the US PGA Championship: T4 (2020), T8 (2021).

Here's what he had to say about his opening round.

"No matter what position I'm in going into tomorrow, I would be grinding it out. This is one of those places where that's what you have to do. You just try and stay in position, make the important par putts and just keep the momentum going. I did a good job of that today.

"I feel like my game is better suited for this kind of test. I get more excited for a tournament like this versus a birdiefest like last week. With that being said, I don't think mentally I would be able to handle playing a tournament like this every single week out here on Tour.

"I think I would have to really lighten my schedule a lot. But going into these events, whether it's an easy or hard course, I'm still trying to stay patient. If I execute appropriately and hit good shots, I'm going to score well whether it's an easy or hard golf course."

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Viktor Hovland has enjoyed by far the best day of this marquee group.

A long-range birdie chance on his final hole, the ninth, never really threatens but it's still a fine 68 for the Norwegian.

Jordan Spieth and Shane Lowry, meanwhile, both finish with bogeys to drop to three over. Not out of it at this early stage but a better second day needed.

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An excellent approach shot from Keegan Bradley at the sixth sets up a fine birdie opportunity, which he rolls home.

It's been 12 years since Bradley won the US PGA Championship in Atlanta on his maiden appearance and he has looked in impeccable touch so far in 2023.

Not to be outdone, Bryson DeChambeau nips it even closer and the 2020 US Open champion continues with a statement of his own.

Birdies apiece for the leaders.

Cam Smith rolls in his birdie try from a dozen feet, Jon Rahm follows him in from about eight - only his second birdie of the round.

But poor old Matt Fitzpatrick's putter is as cold as the frosty weather was first thing at Oak Hill. Two-putt par.