Australian Cameron Smith, Canadian Mackenzie Hughes and South Korean Lee Kyoung-hoon were among a record six players sharing the lead after Thursday’s opening round of the Memorial Tournament.

Americans Luke List, Davis Riley and Cameron Young were also among the co-leaders on five-under-par 67 after 18 holes at the Jack Nicklaus-hosted event at Muirfield Village in Dublin, Ohio.

Garrick Higgo and Erik van Rooyen were the best-placed South Africans (T84) after shooting three-over-par 75s.

“This is about as easy as this place is going to get,” Smith said. “It’s going to be a lot of stressful golf and a lot of grinding over the weekend.”

Smith, a back-nine starter, opened with three birdies in his first six holes, highlighted by a 34-foot birdie putt at the 13th. Between a 28-foot birdie putt at the 1st and an 18-footer at the 9th, he sandwiched two birdies and two bogeys.

“A little bit of a grind,” Smith said. “It was just good to kind of hang in there, make a few birdies, see a few putts going in.”

Lee holed out for eagle from 152 yards at the 9th, then began the back nine with back-to-back bogeys. He answered with consecutive birdies at the par-five 15th and par-three 16th then made clutch pars from 10 and five feet.

“I’m very happy,” Lee said. “I tried to just keep momentum well. Great first nine, especially making eagle.”

Hughes made nine birdies, two bogeys and a double bogey. He closed with three birdies in the last four holes, ending with a 20-footer at the 9th.

“I hit a few loose ones that I’d like to have back, but I did so many good things that it’s easier to forget about those,” Hughes said.

Young, a 10th tee starter, sank a 15-foot birdie putt at the par-three 12th, a 23-foot birdie putt at 13 and holed a 15-foot eagle putt at the par-five 15th. He also closed with a 27-foot birdie putt at the 9th.

“I hit a bunch of good shots early and made kind of the crucial little saves to kind of keep that momentum going with some pars,” Young said. “The eagle was a nice little bonus in the middle.”

List rolled in a 33-foot birdie putt at the par-three 4th and closed with a 15-foot birdie putt.

“That one on the last hole was really special,” List said.

Riley reeled off three birdies in a row starting at the par-five 11th. He rolled in 17-foot eagle putt at the par-five 15th then answered a bogey at 16 with a four-foot birdie at 17.

Japan’s Hideki Matsuyama was disqualified for the first time in his PGA career for using a non-conforming club.

Dabs of white paint used to mark one of Matsuyama’s clubs were applied to freely, spilling from inner grooves onto the face of his club and making it improper.

“When you start applying that much material, that can take spin off a ball or can affect the flight,” PGA rules official Steve Rintoul said. “That’s when they go to nonconforming.”

Bryson DeChambeau fired a 76 in his first round since left wrist surgery after missing the cut at the Masters.

“It wasn’t too bad,” 2020 US Open winner DeChambeau said. “I felt my hand a little bit out there.

“I’m happy to be back. A little sad I didn’t play as well as I wanted. Glad I competed 18 holes without it getting worse. Everything was rusty but I know I can get back in form and climb that mountain.”

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