The superstar American gymnast appeared to slip and nearly landed on her knees trying to land her planned Amanar vault. She finished with a 13.766 score and was seen talking with trainers after the attempt.
The Olympics broadcast said Biles has pulled out of the rest of the team finals.
Jordan Chiles was set to perform for Biles on the uneven bars. Biles’ foot was seen "strapped heavily." The broadcast showed the superstar gymnast in her warm-up gear.
According to multiple reports, Biles was talking with trainers before deciding to pull out. It’s unclear if she was injured in the vault attempt. It’s unclear whether she will compete in the rest of the Games.
The Olympics broadcast said it was not injury related, but instead a "mental health issue."
USA Gymnastics said Biles dropped out over a "medical issue."
"Simone Biles has withdrawn from the team final competition due to a medical issue. She will be assessed daily to determine medical clearance for future competitions," the organization said.
She said afterward she would be back on Thursday.
"I’m OK. Just dealing with some things internally which will get fixed out in the next couple of days," she told reporters in Tokyo.
"No injury thankfully, and that's why I took a step back because I didn't want to do something silly out there and get injured," she said, via Olympics.com. So I thought it was best that these girls took over and did the rest of the job, which they absolutely did — they're Olympic silver medalists. They should be really proud of themselves for how well they did."
Biles, who remarked in a social media post about the pressure she was feeling while in Tokyo, reiterated the stress that has been put on her and her teammates’ shoulders.
"It's been a really stressful Olympic Games as a whole; not having an audience — there are a lot of different variables going into it [the Games]," she said. "It's been a long week; it's been a long Olympic process/year. I think we're a little bit too stressed out. We should be out here having fun, and sometimes that's not the case.
"Today has been really stressful, we had a workout this morning; it went OK but during that five-and-a-half hour wait I was shaking - I could barely nap. I had never felt like that going into a competition before. I tried to go out here and have fun; the warmup in the back went a little bit better but once I came out here I was like, 'no, mentals [sic] not here so I just need to let the girls do it and focus on myself.’"
She did not rule out competing in the next events but was taking things "day by day."
Biles had been the heavy favorite coming into the Olympics but showed that she was human as she only led in a couple of events coming out of the qualification round to start the Games.
She wrote on Instagram she’s found it difficult to brush off the pressure that comes with being among the faces of Team USA.
"It wasn’t an easy day or my best but I got through it. I truly do feel like I have the weight of the world on my shoulders at times," Biles wrote. "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! BUT I’m happy my family was able to be with me virtually. They meant the world to me."
Biles finished her round first in vault and first in the all-around competition, but those were the only categories she was tops in at the end of the day. She was eighth in the uneven bars, third in the balance beam and second in the floor routine.