Jon Rahm and his caddie, Ben Shur, work together during the first round of the Quicken Loans National at Congressional Country Club. (Jonathan Newton/The Washington Post)

All it took was the first shot of the day for Ben Shur to know that the man he was caddying for, the fresh-faced Jon Rahm, was going to have a good round at the Quicken Loans National. As the ball flew over the water and onto the green on the par-3 10th hole, Shur took out his scorecard and wrote down one simple phrase.

“Jon will not have a bogey today.”

Nearly five hours later, Shur was proved right and then some; Rahm, a native of Barrika, Spain, was atop the leader board with a 7-under-par 64 after his first round as a professional golfer.

Rahm, who turned pro this week after claiming the silver medal for low amateur last weekend at the U.S. Open, hit 14 of 18 greens in regulation and birdied three of his final seven holes. Storms delayed the start by 2 hours 15 minutes, so play continued well into Thursday evening, but no one matched Rahm’s number.

Amateur Jon Rahm of Spain poses on the 18th green after winning the medal for low amateur after the final round of the U.S. Open at Oakmont Country Club. Rahm then turned pro, and holds the late afternoon lead in the Quicken Loans National. (Andrew Redington/Getty Images)

He went to sleep with a one-shot lead over Venezuelan Jhonattan Vegas and a two-shot advantage over a host of players at 5 under, including Ernie Els, Bill Haas and Naval Academy graduate Billy Hurley III, a Leesburg native.

Shur’s prophecy Thursday wasn’t just a lucky guess. It was the product of a relationship that began when Shur and his roommate, former Arizona State golfer Chris Russo, picked up Rahm from the airport as he arrived in the United States for his freshman year at ASU in 2012.

Rahm, Shur and Russo went to see a movie, “The Bourne Legacy.” Rahm, tired and jet-lagged, said he barely understood what was going on. But on that first outing, he and Shur began to establish their mutual love for golf, and a friendship blossomed.

“If you ever need help with homework, school, getting around,” Shur said to Rahm, “just let me know.”

And as Rahm’s national profile rose, he also helped Shur get better on the links. The pair would spend hours working on Shur’s chipping game as Rahm prepared for his college matches. Eventually, Shur walked on to the Sun Devils golf team. And in 2014, Rahm asked Shur to caddy for him at the Spanish Amateur, where things really began to click for the duo.

“He was seven back going into the last day and he won by three,” Shur said. “Living with him for those couple of weeks, it brought us closer. We think similarly. We have the same morals.”

Rahm made sure to tell Shur how much he appreciated him by his side.

“My goal is to make sure you’re treated as the best caddie,” Rahm told Shur.

From there, Shur began to caddie regularly for Rahm. The inside jokes, the TV shows, the relationship advice, “the guy stuff” that they talked about on the course only brought them closer.

“He knows me better than anyone,” Rahm said. “He knows the way I think, and he knows the way I play golf. He knows exactly what I’m thinking at every point. A lot of times, he’s already grabbed the golf club I’m going to hit before I even say. Having someone who knows me so well, it’s certainly an advantage. He knows what I can and can’t do, and he knows when to stop me on my feet when it’s needed.”

The results certainly manifested themselves Thursday as Rahm kept his poise during a bogey-free round that included seven birdies. It’s Rahm’s level mind-set that Shur said brings out the player’s best on the greens.

“I would say about five months ago, my expectations were really high, but coming into this moment, I worked with my mental coach to keep — we basically just narrow it down to enjoying it and learning as much as I could,” Rahm said. “I’ve been thinking like that for the last month and trying not to have high expectations.”

After a successful first day in Bethesda, Rahm said he was not going to deviate from his plans of going to watch a movie with his parents, his girlfriend, and Shur. But as the tournament moves forward, more and more eyes will be on the 6-foot-2 new kid on the block. It’s a pressure that Rahm said he brushes off — he’s avoiding social media — but the golf world will be watching.

And by his side will be his best friend. On the first tee — Rahm’s 10th hole of the day — he drove the ball 315 yards into the fairway, the farthest in his group of Hurley and Sam Saunders. As the gallery applauded, Rahm looked back at Shur. Almost on cue, both smiled wide as they began to speak over each other.

“I smoked that,” Rahm said.

“You smoked that,” Shur said.