Japan's Hideki Matsuyama leads the field after the opening round of the Men's Golf competition at the Paris Olympics, but Team USA icon Michael Phelps won the day.

The most decorated Olympian in history soaked in the action at Le Golf National. Phelps joined a chorus of PGA Tour and LIV Golf stars — including Scottie Scheffler, Xander Schauffele, and Rory McIlroy — who praised the surprisingly raucous atmosphere in Saint-Quetin-en-Yvelines.

“You can feel the energy, you can feel the electricity,” Phelps said on the NBC Sports telecast. “The Olympics is about bringing people together, and that's what we're feeling out here.”

Phelps made sure to check out France's Matthieu Pavon's first tee shot, as supporters serenaded him with the host country's national anthem.

“When Pavon came up to the tee and the whole entire audience just started belting out, it was absolutely incredible,” Phelps said. “I mean, the hair on my arms was sticking straight up, and I think it really shows what the Olympics is.”

“It was awesome,” added Collin Morikawa (-1), who played with Pavon. “Honestly I didn't know what to expect. First tee obviously having Matthieu Pavon there, a Frenchman, made it incredible.”

Phelps was more than just a super-fan with a deep appreciation for the Olympics. The 23-time gold medal winner was there as a parent, a friend and a dedicated student.

“For me, I was pumped to watch Ludvig (Aberg) – somebody who's really kind of made a name for himself over the last year or so on Tour,” Phelps said. “I love his approach to the game. Some of his drills that he does, I've tried to do them, though not as well.”

Aberg, the Swedish phenom, posted a 3-under par — five strokes behind Matsuyama (-8) in his first Olympics action. Reigning gold medalist and Open Championship winner Xander Schauffele (-6) sits in second. Three golfers, including South Korea's Tom Kim, another friend of Phelps', shot a 5-under 66.

Rahm, representing Spain, and Scheffler are among the eight golfers tied at 4-under. (Team USA's fourth delegate, Wyndham Clark, shot 4-over).

“Rahmbo is a good friend of mine, and Wyndham for Team USA,” said Phelps. “For me, it's just seeing these guys up close. I'm a golf nut, so being able to just pick up on ball position, grip, length of backswing, whatever it might be.”

Phelps implied the technical challenge of learning golf fills a void left by his retirement from swimming. Naturally, the Olympics legend is diving head-first into the sport to a similarly obsessive degree.

“I'm a super technical person,” he said, per the PGA Tour's website. “That's how I had to be in my sport, so it's kind of nice that way. I gravitated towards this, and here we are. I'm a psycho in the game and I love it.”

“I will go back and look at those videos, break 'em down frame by frame, just to see where they are in certain spots, where their hips turn, where their shoulder is, all that stuff. And hopefully it translates to helping me become a better golfer. I'm a 6 (handicap) right now. I want to get to a scratch, but I know I’ve got to put a lot of work in.”

For whatever reason, I won't doubt Michael Phelps.