Kyle Snyder won the gold medal by defeating Khetag Goziumov in the 97kg freestyle wrestling final. (Jonathan Newton/The Washington Post)

So long ago that he cannot quite remember when, Kyle Snyder set a countdown clock on his phone, marking every second until the Rio de Janeiro Olympics. Late Sunday afternoon at Carioca Arena 2, Snyder wore a gold medal around his neck and wondered what had happened to all those days and minutes. He is just 20, but he has learned a fundamental part of life: He knows how quickly time slips past.

“Everything has gone by so fast,” Snyder said. “I’ll be looking forward to something, and before I know it, it’s here and I’ve competed.”

The world moves faster for Snyder than most. On the final day of the Rio Games, Snyder became the youngest U.S. wrestler to win an Olympic gold medal, the culmination of his sudden rise to the top of the sport. In the title bout, Snyder defeated Azerbaijan’s Khetag Goziumov, 2-1, fending off a 33-year-old former world champion who won bronze at each of the past two Olympics.

“It’s incredible,” said American Frank Molinaro, who lost a 65-kg bronze medal match. “The kid is young, and he’s wrestling men out there. And he’s the man. He’s throwing these guys down. He’s breaking them.”

When he left the mat, Snyder leaped into a crowd of family friends. His parents, Steve and Tricia, congratulated Snyder and told him they loved him. Snyder did not want to stay long because he is claustrophobic and felt supporters closing in for hugs. Many of them waved American flags. One unfurled a Maryland state flag.

Snyder grew up in Woodbine and attended Good Counsel High until his senior year, when he moved to the U.S. Training Center in Colorado Springs after a 179-0 high school career. He cannot remember the last day he went without dedicating himself, in some way, to wrestling.

And yet his initial victory unfolded without a release of emotion, the kind athletes from all over the world had displayed for the past 17 days.

“Maybe I was in shock,” Snyder said. “I don’t know. I was definitely really happy. Happier than I’ve ever been on a wrestling mat.”

Snyder reached the final on the strength of his superior conditioning. In the semifinals, Snyder trailed Georgian Elizbar Odikadze 4-0 at the break. He punished Odikadze in the second period, pushing him out of bounds and throwing him to the mat. Odikadze incurred a one-point penalty because he delayed in walking back to the center for a restart, panting on one knee. Snyder broke him.

In preparation for the tournament, U.S. coaches cited three wrestlers who they believed posed threats to Snyder. One was Goziumov, whom Snyder had lost to at an international tournament in July.

Snyder planned to be more aggressive shooting for legs, and he believed he needed to score first to prevent Goziumov from using his strength to play defense. With 1:10 left in the first period, Snyder pushed him out to take the lead 1-0. At the break, Snyder stomped to the center of the ring with several seconds to spare, a common act and unintentional testament to his work ethic.

“I don’t need 30 seconds,” Snyder said. “I’m ready to roll. I could go six minutes straight.”

Snyder added another point on a stalling penalty early in the second, then incurred one himself. He had to hold off Goziumov for one final minute. As Goziumov probed him for weaknesses, Snyder thought, “This guy is crazy strong.” But he resolved not to let him earn a takedown.

“I wasn’t going to let another point go up on that board,” Snyder said. “Unless it was me scoring.”

Snyder did not let another point on the board. He had supplanted Henry Cejudo, who won gold as a 21-year-old at the 2008 Beijing Games, as the youngest U.S. Olympic wrestling champion.

The gold medal provided another new height on Snyder’s rapid ascent. As a freshman at Ohio State in 2015, Snyder lost in the NCAA championship match. Six months later, at 19, he won the world championship in Las Vegas. He claimed an NCAA title in the heavyweight division this year, then beat 2012 gold medalist Jake Varner at the U.S. Olympic trials in April.

Snyder has stated his goal is to be the best wrestler ever, and after Rio, it exists as something more than fantasy. Just three American wrestlers, George Mehnert, Bruce Baumgartner and John Smith, have won multiple gold medals. Snyder likely will be the favorite in four years in Tokyo, and by 2024, he will be just 28. It might be premature to raise the possibility, but Snyder stands a chance to become the first American to win three.

“Does it start him on that plane?” USA Wrestling Coach Bruce Burnett said. “Yes, it does. With that comes other challenges. Everything that they do from this point on takes time away.”

The biggest challenge Snyder faces now will be managing the torrent of success. Jordan Burroughs, the face of American wrestling, suffered two shocking defeats this past week trying to defend his 2012 gold. Snyder’s dedication to wrestling and his grounding justify the belief he can withstand pressure. Snyder’s older brother graduated from West Point and is in Ranger school. His younger brother is heading to Ohio State to wrestle with Snyder. At a dinner Saturday night, Burnett told Steve and Tricia, “Thank you for the work you put into your kids.”

For Snyder, the key will be focus. He used to grow nervous before wrestling his toughest opponents because he viewed them as a threat to victory and accolades. He decided instead to shift his focus.

“It just comes down to what you value,” Snyder said. “If you value winning and gold medals, the thing you’re going to fear the most is losing. That causes you to tense up. It doesn’t allow you to wrestle to the best of your ability. But I am very strict in the way I think about the sport. I do it because I love it. I do it because I want to be the best that I can be at it. If I were to wrestle for however long I can possibly wrestle and I don’t win another one because people are better than me, then people are better than me. But I’m not going to spend time thinking about that.”

Life will keep moving too fast for him to worry. On Saturday after he made weight, Snyder refreshed his email and saw a note from one of his Ohio State professors, telling him which books to buy. He will head to campus for his junior year soon. He might one day become the best wrestler in his country’s history. He already is a gold medal winner, and for one night, he didn’t have to look forward to anything.