OAKMONT, Pa. – J.J. Spaun left THE PLAYERS Championship in March defeated yet invigorated.

The PGA TOUR journeyman had just experienced his most crushing loss to date – a playoff defeat that was all but handed to Rory McIlroy after a water ball at the iconic par-3 17th.

Yet, for the first time in his career, Spaun felt comfortable with the idea of contending and winning a big event. That he was good enough and deserving enough to lift the trophy in the end. It’s a level of self-belief many assume pro athletes innately possess, an irrational confidence born of supreme talent that got them to the TOUR – a level that only a fraction of golfers reach. Spaun needed to learn it, and the fruits of that labor bore out Thursday at the U.S. Open.

Despite his recent hot-and-cold form and an historically difficult Oakmont Country Club that admittedly had him “pretty nervous,” Spaun summoned the best major round of his life – a bogey-free, 4-under 66 to take the lead in the U.S. Open lead through the morning wave.

“I don't know why this is happening … at this point in my career,” Spaun said afterward, a pro since 2012.

It begins with that belief. There’s no faking a lead at a major championship, particularly one as exacting as the test Oakmont presented in the first round. In previous seasons, Spaun was uncomfortable being chased. Round 1 of a major isn’t exactly the back nine on Sunday, but it’s a start.

Spaun spent pretty much his entire round alone at the top of the leaderboard. As others fluctuated around him, Rory McIlroy and Bryson DeChambeau included, Spaun stayed rock solid. He chipped in for a birdie on his first hole, No. 10, then took advantage of the lone hole that was playing under-par at the time, the par-5 12th, and added two more birdies to turn in 4-under 31. It was the best opening nine holes of the 10 U.S. Opens held at Oakmont. Then Spaun made all pars on the front nine, the harder of the two sides, to preserve a 4-under round.

The star of the show was Spaun’s putting. He made five par putts of 7 feet or longer to maintain his momentum, gaining nearly four strokes on the greens, the best mark in the field.

“Today was one of my best putting days I've had maybe all year,” Spaun said.

A short-game lesson he received on Monday also played a factor in his flawless scrambling. Longtime friends but never work partners, Spaun and Josh Gregory linked up this week at Oakmont. Gregory believed he could help Spaun solve a few of his issues, and Spaun was receptive to learning more. Over the course of one lesson, they shortened Spaun’s backswing, and Gregory gave him tips on how to play the brutal lies that players regularly face at Oakmont. When Spaun chipped in on the first hole Thursday, his caddie Mark Carens turned to Spaun and said, “Nice chip, Josh.” Spaun ranked inside the top 10 of strokes gained around the green on Thursday.

“He’s got some great hands, just needed some guidance,” Gregory told PGATOUR.COM via text.

The first round is just the latest in what’s become a career year for Spaun. He began the year with a T3 finish at the Sony Open in Hawaii, finished a distant runner-up to Joe Highsmith at the Cognizant Classic in The Palm Beaches, then did what he did at THE PLAYERS Championship. He nearly ended the tournament in regulation, just missing a birdie putt on the 18th hole that would’ve won him the tournament. Spaun added another top-10 finish last month at the Charles Schwab Challenge.

“I can perform on the biggest of stages and handle it with the pressure,” Spaun said. “There's going to be a lot of pressure this week, too, and hopefully I can rely on those experiences.”

Contending at a major is new territory for Spaun. He had never played a bogey-free round in his major championship career until Thursday. Nor has he ever led, or come close to leading, a major round. His best finish is a T23 at the 2022 Masters. That his first lead has come at Oakmont is surprising even to Spaun. He did not play the U.S. Open in 2016, so his knowledge of the course was only that it was incredibly hard.

“It's hard to not hear the noise and see what's on social media and Twitter and all this stuff. You're just kind of only hearing about how hard this course is. I was actually pretty nervous,” Spaun said. “But I actually tried to harness that, the nerves, the anxiety, because it kind of heightens my focus, makes me swing better, I guess. I don't know, I kind of get more in the zone, whereas if I don't have any worry or if I'm not in it mentally, it's kind of just a lazy round or whatever out there. I like feeling uncomfortable.”

He will have many more uncomfortable moments over the next 54 holes. Carnage is lurking on every hole at Oakmont. Chipping in and holing a bevy of mid-range par putts likely isn’t a sustainable path to victory, but any path to victory starts with belief.