Simone Biles' bid to claim her first Olympic gold medal of the Tokyo Games suffered a major setback as she was forced to withdraw after one rotation of the women's team final due to an unspecified injury.
Biles misjudged her opening vault, scoring 13.766, the lowest of the first rotation, before leaving the floor briefly with the US team trainer.
Although the 24-year-old returned, she put on her tracksuit and did not compete in the Americans' next apparatus, the uneven bars.
On Sunday, Biles had qualified for every individual apparatus final and finished top of the all-around standings, staying on track for a potential six golds in the Japanese capital.
But she looked far from dominant at times, as the US team were eclipsed in the qualifying standings by the Russian Olympic Committee, the first time since 2010 that they had been pipped to top spot.
And Biles' mistake on the vault has renewed doubts over her ability to repeat her stunning performance in Rio, where she won four gold medals.
US reserve Jordan Chiles stepped in to replace Biles, but the US trailed the team from the ROC by a relatively wide 2.500 points after two of the four rotations, raising the likelihood that they would fail to win women's team gold for the first time since Beijing 2008.
