Reigning champion Simone Biles has withdrawn from the individual all-around gymnastics competition at the Tokyo Olympics, USA Gymnastics said Wednesday.That comes shortly after Biles' sponsor, Athleta, rallied behind the American gymnast after she dropped out of the women's team final on Tuesday.Biles dropped out of the team final Tuesday after a wobbly first vault.USA Gymnastics initially said she had withdrawn from unspecified "medical issue," but Biles later clarified that she needed to focus on her mental health.She said the pressure of living up to expectations left her no choice.Fighting back tears, she told reporters "I do not trust myself anymore."Athleta said in a statement after "We stand by Simone and support her well-being both in and out of competition... Being the best also means knowing how to take care of yourself."There was an instant outpouring of support for Biles on social media and White House Press Secretary Jen Psaki tweeted, "Gratitude and support are what @Simone_Biles deserves. Still the GOAT and we are all just lucky to be able to see her in action."Meanwhile, U.S. Olympic and Paralympic Committee CEO Sarah Hirshland celebrated Biles for her bravery, writing "We applaud your decision to prioritize your mental wellness over all else, and offer you the full support and resources of our Team USA community as you navigate the journey ahead."The spokesman for the IOC said Wednesday that it had quote "huge respect and support" for Biles, and that "more could be done" for athletes' mental health.The U.S. women's gymnastics team went on to win the silver medal.