Japan's reigning Olympic all-around gymnastics champion Daiki Hashimoto had been on an emotional roller-coaster for months.

Back in May, injury had forced him to suddenly pull out of the NHK Trophy - the sport's marquee tournament in Japan - that he hoped would be his chance to dress-rehearse his routines ahead of the Paris Games.

Still nursing a far-from-healed finger injury, he joined other Olympic-bound athletes at the team's training camp even though he wondered whether he would be able to lead the five-man team to the gold medal that his nation expected.

"To be honest, I was starting to lose confidence," Hashimoto told reporters on Monday. "When the camp ended, I still couldn't visualise how I was going to win that gold."

That sense of doubt seemed to have disappeared two days ago when Hashimoto stepped into the Bercy Arena in Paris, beaming and waving to the adoring fans.

But the confidence was short-lived.

On the high bar, Hashimoto botched his dismount by landing on his hands and feet, dashing his chance of reaching the final to defend the title in the apparatus.

"I became a drag on the team and that felt really heavy again," he said.

Japan had been hoping to top the qualifying standings to underline their title credentials but they had to settle for second place behind China.

Through the difficult moments, it was his teammates' unwavering determination and constant encouragement that carried him through, Hashimoto said.

"Every time I opened the doors to the training grounds, all of them would talk about how they wanted to win the gold medal. Seeing that, I really felt from the bottom of my heart that I wanted to fight for this team."

On Monday, with that medal at stake, Hashimoto needed one more lift from his teammates.

In an error that drew a collective gasp from the arena, Hashimoto fell off the pommel horse, setting Japan back against a formidable Chinese side. In fact Hashimoto's lowly score of 13.100 left his country trailing in fifth place at the halfway point of the final.

"The moment I fell I thought to myself, 'Oh no, we're going to lose the gold again because of me'," said Hashimoto, who was part of the Japanese team that finished second behind Russia at the Tokyo Games.

"But when I finished, (teammates Takaaki) Sugino and (Kazuma) Kaya said to me, 'Don't give up. We can still do it.'"

With only one of the six apparatuses left to go, China's gold medal seemed all but certain as Japan trailed by more than three points - a massive deficit that could only be overcome provided the Japanese executed a series of near-flawless routines and also required Chinese gymnasts to suffer some major mishaps.

Fortunately for Japan, that is exactly what happened on the horizontal bar.

Xiao Ruoteng completely botched his dismount by landing on both knees to earn his lowest score of the day of 13.433.

Minutes later his Chinese teammate Su Weide suffered two crash landings from the bar, giving Hashimoto a chance at redemption and his team a shot at gold.

The last of his team to compete, Hashimoto put in a solid 14.566 performance to give his team a total of 259.594 points. It left the final Chinese competitor requiring an improbable 15.265 just to tie with Japan. Zhang Boheng fell well short of that target.

"I'm so incredibly happy. It's different from an individual medal," Hashimoto said.

"Everyone's hugging each other like crazy, and then hugging again even though we just hugged. I feel like this medal has deepened our strong bond even more."