Wyndham Clark fired a course-record 64 at Shinnecock Hills on Thursday to seize the first-round lead at the 2026 US Open, putting up a score that even the defending champion himself described as almost impossible to believe given the conditions.

Clark, who won the US Open at Los Angeles Country Club in 2023, made eight birdies against no bogeys in a round played in the gusty late-afternoon session as conditions softened slightly compared to the morning. He finished five shots clear of Hideki Matsuyama and Tommy Fleetwood, who both carded 69 to sit tied for second.

Shinnecock Hills, the 123-year-old course on Long Island hosting a major for the sixth time, has never yielded a round lower than 63 in competition. Clark’s 64 bettered that mark by one and came on a day when the course played to a stroke average of 73.2 for the entire field, making his score all the more remarkable.

He hit 16 of 18 greens in regulation, his irons razor-sharp from the first hole, where he stuck a nine-iron to two feet for the opening birdie. He went out in 30, turned to find the wind had eased marginally, and continued attacking in the second nine. His lone scare came at the 16th, a par three where he hit a mid-iron long and needed a deft chip to save par.

World number one Scottie Scheffler had a day that reflected the difficulty everyone else faced. He carded a 71 after a double bogey on the 11th hole from a buried lie in the deep fescue rough. Rory McIlroy, seeking the career grand slam, shot 72 and said afterward that conditions in the morning were among the most demanding he had experienced in a major. Xander Schauffele, the reigning Masters and Open champion, made four bogeys on the back nine and finished at 73.

Clark said after his round that he had made no particular adjustments to his game plan for Shinnecock. He said he trusted his reads, hit his targets, and the ball went in the hole. He acknowledged the score was far beyond what he had set as a realistic target when he arrived Wednesday.

The USGA said it was considering firming the greens slightly overnight if conditions allowed, having held back from aggressive setup on day one because of earlier-than-anticipated wind. Shinnecock’s greens can reach unplayable speeds when the combination of sun and wind is at its most aggressive. The 2004 US Open at the same course became infamous for setup decisions that made putting on some greens a matter of luck rather than skill.

The cut is projected to fall around four over par after day one scoring. The second round begins Friday morning with Clark in the final group teeing off at 2:45 p.m. Eastern. He will be paired with Matsuyama and Jon Rahm, who carded a 70 on Thursday and sits six shots back.

Clark’s performance gives him a significant cushion heading into the weekend, though five-shot first-round leads at US Opens have historically shrunk considerably by the time Sunday arrives. His 2023 title run at LACC was defined by a final-round 65 under pressure, suggesting he is not a player who tends to buckle when the moment demands.

The leaderboard will reset considerably once morning conditions return on Friday. The USGA said wind forecasts for Saturday and Sunday were for stronger gusts, which typically makes Shinnecock’s narrow fairways and fast greens exponentially more punishing for the field chasing Clark.