US star gymnast Simone Biles was left weighing her Olympic future on Tuesday after dropping out of the women’s gymnastics team final at the Tokyo Games following one disappointing vault, saying she had to focus on her mental health.

Her withdrawal handed Russia’s squad a path to the gold medal and ended American domination of the event for more than a decade.

Biles, 24, said she pulled out because she wasn’t in the right place mentally to perform the difficult and often dangerous skills she is known for, after feeling so much pressure to be successful. She had been struggling with the stress of being the greatest gymnast in history, she said, and outside expectations were just too hard to combat.

Before the event on Tuesday, she said she began “fighting all of those demons,” and couldn’t hold them back.

“At the end of the day, I have to do what was right for me,” she said, adding, “It just sucks that it happened at the Olympic Games.”

She said she was not certain whether she would compete again at the Tokyo Games.

For so long, Biles had appeared invincible, racking up 30 world and Olympic medals in a spectacular career that was expected to come to a closely-watched climax in Tokyo as she launched a bid for six gold medals that would make her the greatest female Olympic champion of all time.

But just as her quest got underway on Tuesday, it all unravelled, the 24-year-old later conceding that the pressure of living up to expectations had left her no other choice but to stop after one vault.

The retirement from the team competition has left Biles’ future participation at the Tokyo Games in limbo. She had been expected to feature in all six events at the Games that included a defence of her all-around crown on Thursday followed by four apparatus finals next week.

“I do not trust myself anymore,” said Biles, fighting back tears as she met with the world’s media. “I have to focus on my mental health.

“There is more to life than just gymnastics. We have to protect our mind and our body rather than just go out there and do what the world wants us to do.”

What many wanted to see was Biles take the first step towards six gold medals that would make her the greatest female Olympian of all time.

But what they saw instead was a stunning breakdown as Biles ended her evening after one vault, her score of 13.766 the lowest on the US team that without their leader went on to surrender the team title to Russia, settling for silver. Britain won the bronze medal.

The last time the US lost a team final in the Olympics or world championships was back in 2010, to Russia. Since then, the US has been far ahead of the world in the sport, winning world championships and Olympics by at least 4 points, a wide margin in a sport where competitors are often divided by less than a single point. At the Rio Games, the Americans crushed the Russians by more than 8 points.

On Sunday, after Team USA’s uninspired qualification effort, Biles had posted on social media that she felt she was carrying the weight of the world with the pressure of chasing medals continuing to build.

“It wasn’t an easy day or my best but I got through it,” Biles 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!”

Robert Andrews, a mental training expert who worked with Biles for about four years, told Reuters he suspected stress played a large factor in Tuesday’s outcome.

“Gymnastics probably more than any other sport... requires laser, pinpoint focus,” said Andrews. “Being a global presence, the greatest of all time, all that starts creating interference.”

He added: “If she’s this stressed out to where she has a mental block, I would approach it with caution.”