Kohei Uchimura, Japan’s gymnastics hero, slips, falls and loses out on a medal.

TOKYO — Nearly everyone in the gymnastics arena at the Games — other gymnasts, coaches, arena workers and reporters — stopped what they were doing on Saturday to watch Kohei Uchimura of Japan, considered one of the best male gymnasts ever, perform his high bar routine.

At the start of his fourth Olympics, Uchimura, one of the most revered athletes in Japan, swung around the bar and soared over it in his usual daring and dazzling way. But then his hands slipped during a fast — maybe too fast — pirouette requiring intricate handwork, and spectators gasped.

Uchimura fell, landing on the mat with a loud smack and ending his hopes of winning a gold medal at his home Olympics. His fall, during the men’s qualifying event, was emblematic of how the Summer Games have gone for Japan: so much hope, followed by a huge letdown. Uchimura did not qualify for the final.

At the 2016 Rio Games, he won the all-around to become the first male gymnast to retain his Olympic title in the event in 44 years. From 2009 to 2016, he didn’t lose an all-around at the world championships or the Olympics. Leading up to that dominance, he won the silver medal in the all-around at the 2008 Beijing Games.

Uchimura, 32, has been a staple at the top of the sport for more than a decade. But at these Games, he was competing only in high bar, not as part of Japan’s team. His Olympics — and most likely his remarkable career — are over.

After his fall, Uchimura fist-bumped a few teammates and walked out of the arena, silently passing a giant set of Olympic rings on the wall before disappearing under the stands.

Through two of three qualifying rounds, Japan was in first place in the team competition. China was second and Russia was third, with all three teams separated by about one-tenth of a point.