Simone Biles appears increasingly unlikely to return to action at the Tokyo Olympics after announcing her withdrawal from Sunday's individual finals in the vault and uneven bars.
The 24-year-old has not competed since she pulled out of the women's team final on Wednesday after one rotation, citing mental health concerns.
She watched on from the stands at Tokyo's Ariake Gymnastics Centre as her team-mates Jess Carey and Sunisa Lee competed in the women's all-around final on Friday, which Lee went on to claim the gold medal in.
USA Gymnastics said in a statement: "Today, after further consultation with medical staff, Simone Biles has decided to withdraw from the event finals for vault and the uneven bars.
"She will continue to be evaluated daily to determine whether to compete in the finals for floor exercise and balance beam.
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"We remain in awe of Simone, who continues to handle this situation with courage and grace, and all of the athletes who have stepped up during these unexpected circumstances."
Biles is still scheduled to compete in the floor final on Monday and the beam the following day.
The Ohio-born athlete said in a social media post on Friday that she was continuing to suffer from a phenomenon known as 'twisting'.
The four-time defending Olympic champion wrote: "It has never transferred to bars and beam for me. This time it's literally in every event which sucks.
"(You) literally cannot tell up from down. It's the craziest feeling ever, not having an inch of control over your body."
If Biles does rule herself out of the floor final, Britain's Jennifer Gadirova will step up from first reserve to join her sister Jessica in the competition.
Biles decision a 'seminal moment' in Olympics history
Vicki Aggar, chair of the British Athletes Commission, has hailed Biles' courage to speak out and raise awareness of the importance of mental health and believes it could prove to be an intervention far greater than her gymnastics feats.
"Like us at the British Athletes Commission, many of Biles' peers see this as a potentially seminal moment in sport," Aggar said.
"For one of the highest-profile names at an Olympic Games to, whilst in the running for a fifth career gold medal, put her mental health first is a huge statement.
"Her courage can now ensure that the conversation can move on even further; that athletes can feel more comfortable speaking out about such issues; that decision-makers within sport will find it impossible not to factor in mental health considerations when building an environment for training or competition.
"For all Simone Biles' countless extraordinary achievements, pushing forward the conversation on mental health and providing a courageous and unprecedented example to current and future athletes around the world, may just turn out to be her most important."