TOKYO (REUTERS) - Simone Biles' future participation at the Tokyo Olympics was in doubt on Tuesday (July 27) after she dropped out of the women's team final after one vault as the United States surrendered the gold to Russia.

After a disappointing vault in the first rotation of the women's team event, the American was signified by an 'R' on the competitor list before the bars began, indicating she would not continue in the competition.

Later, she said she was unsure whether she would compete on Thursday in the women's all-around event.

"After the performance I did, I just didn't want to go on," said Biles, fighting back tears as she met with the media. "We are going to see about Thursday.

"I'm just trying to gear up for the next test."

USA Gymnastics said Biles had withdrawn because of a "medical issue", and would be assessed daily.

The late-night drama was a fitting end to a day which had begun under the threat of a storm and featured the loss of the face of these Games, Japan's tennis superstar Naomi Osaka.

It was a stunning and disappointing start to the Olympics for the mighty American women's team, who had expected to dominate the final as they had not been beaten in a major team competition since 2011.

But the entire event was turned on its head in an instant when Biles, the world and Olympic all-around champion, completely mistimed her opening vault to earn a low score of 13.766.

It was a setback the US never recovered from as Russia, competing as representatives of the Russian Olympic Committee (ROC) because the country was stripped of its flag and anthem for doping offences, claimed the team title for the first time since the Unified Team at the 1992 Barcelona Games.

The US, winners in 2012 and 2016, settled for silver and Britain claimed the bronze.

Biles struggling

There were signs that Biles had been struggling to live up to her high standards.

At the US Olympic Trials in June, she was left in tears when she was unable to come to grips with the disappointment of her performance.

The pressure of chasing medals continued to build in Tokyo, Biles posting on social media after Sunday's uninspired qualification effort that she felt she was carrying the weight of the world.

"It wasn't an easy day or my best but I got through it," she wrote on Instagram. "I truly do feel like I have the weight of the world on my shoulders at times.

"I know I brush it off and make it seem like pressure doesn't affect me but damn sometimes it's hard hahaha!

"The Olympics is no joke!"

There was an instant outpouring of support for her on social media.

"Gratitude and support are what @Simone-Biles deserves," White House Press Secretary Jen Psaki said on Twitter. "Still the GOAT and we are all just lucky to be able to see her in action."

Disappointing score

Biles' competition got off to a bad start on the vault in the first rotation. All three Russians scored higher, as did her team mates.

Stunned and close to tears, Biles, gold-medal winner on the vault at the Rio Olympics, sat dejected in a chair as coaches and teammates surrounded her before moving onto the uneven bars, the US sitting second, 1.067 points behind their Russian rivals.

Biles, however, appeared to be more than simply disappointed, leaving the arena with the trainer as her teammates warmed up.

By now coaches and officials sprinkled throughout the Ariake Gymnastics Centre had begun to chatter as Biles reappeared minutes later slipping into her warm-up gear.

While she left the arena uncertain if she would be back, some of here fellow gymnasts fully expect to see her on Thursday.

"This is very unusual for her, but if you're under a lot of pressure it can affect your body," said Japan's Mai Murakami. "I think she decided to save her body for later this week, for the all-around and apparatus."

If Biles does win five in Tokyo, she would join four athletes on nine - Latynina, swimmer Mark Spitz and track and field athletes Paavo Nurmi and Carl Lewis.