A Cantlay could win a USGA championship this year, and it won’t be Patrick.

Jack Cantlay, the 18-year-old younger brother of the reigning FedExCup champion, opened the U.S. Junior Amateur with a 5-under 67 Monday at Bandon Dunes. His opening round of the 36-hole stroke-play portion featured a final-nine, 8-under 28 on Bandon’s front nine, a new championship record for lowest nine-hole score.

The previous record was 29, held by Eric Bae (2014) and Yuki Moriyama (2018).

Cantlay started slow, 4 over after eight holes, before making birdie at the par-5 18^th hole. That’s when he saw friend and fellow playing competitor, Luke Powell, who asked how Cantlay was playing.

Once Cantlay answered, Powell simply said, “Turn it around.”

“So, I birdied the first hole,” Cantlay said, “and made a lot more 3’s on that side.”

Cantlay’s front nine was highlighted by a 45-foot eagle make at the par-5 third hole. He capped his record side with a 30-yard chip-in eagle at the par-5 ninth.

“I think that’s the first time I have broken 30,” Cantlay said. “It’s a first time for everything, I guess. It’s just another round of golf, sometimes you play good and sometimes you play bad. Today I played good.”

Cantlay sits a shot off the lead, which is shared by Erich Fortlage, Grant Lester and Harvey Young, heading into his final round of stroke play Tuesday at Bandon Trails, the stroke-play co-host. The top 64 players advance to match play, which begins Wednesday.

An incoming freshman on the Long Beach State golf team, Cantlay prepared for his first USGA championship by traveling to Scotland to watch his oldest brother (his other brother, Nick, plays on PGA Tour Canada while his sister, Caroline, also played college golf) compete in The Open at St. Andrews. Patrick tied for eighth, his first major top-10 since 2019, while Jack got in a few practice rounds on true links layouts such as Royal Dornoch and Castle Stuart.

The advanced prep is paying off so far as Jack looks to do something Patrick never did. Patrick was a former No. 1 amateur in the world, made the U.S. Walker Cup team in 2011 and twice reached the semifinals of the U.S. Amateur, including in 2011 when he lost to Kelly Kraft in the final. However, Patrick only advanced as far as the Round of 32 at the U.S. Junior – that came in 2009, his first USGA championship at age 17.

The youngest Cantlay isn’t getting ahead of himself. After all, he is a Cantlay.

“Every round of golf is the same,” Jack said. “Just try and go out and do what I did today.”