Simone Biles, 24, picked up four Olympic gold medals in Rio de Janeiro in 2016. In the team final in today's jumping competition, she did not really get her acrobatics.
The 24-year-old failed with the landing in the initial moment - and received a point deduction.
The Russian team could then pull away in a points lead.
Biles was really disappointed afterwards.
She then chose to leave the competition together with one of the leaders and was suddenly removed from the team before the ensuing moment.
It is still unclear why she left, but Biles is said to have been seen with a bandaged foot, reports The Guardian.
The sport's biggest star
She is considered the greatest gymnast in the world and has won 19 World Cup gold medals.
The competition is ongoing.