The world has come to expect nothing less than breathtaking perfection when Simone Biles launches herself rocket-like over the vault.

So the fleeting expression of disbelief that crossed the champion gymnast’s face as she completed the less than perfect move during the women’s team final at the Tokyo Olympics on Tuesday was shared by all.

Here in the US, the NBC commentator, who only seconds earlier had been piling on the superlatives, was silent as Biles lost control in mid-air, failed to complete her intended two-and-a-half twists and then stumbled as she landed.

‘Wow,’ was all he could say.

And it was ‘wow’ indeed as the 24-year-old superstar didn’t just walk away from the vault, but from the team event – in which she was captain – saying she wasn’t mentally prepared to compete and was battling ‘demons’.

Biles’s departure not only left the US without its top-scoring gymnast but, in a plot twist worthy of Hollywood, allowed bitter rivals Russia to take gold.

Appearing on US TV yesterday, her team mates defended her decision to ‘focus on her mental health’, insisting she is ‘not a quitter’.

The world has come to expect nothing less than breathtaking perfection when Simone Biles launches herself rocket-like over the vault. So the fleeting expression of disbelief that crossed the champion gymnast’s face as she completed the less than perfect move during the women’s team final at the Tokyo Olympics on Tuesday was shared by all

However, two of them, Jordan Chiles and Grace McCallum admitted they’d been left on the ‘verge of tears’ at the consequences. Chiles had to compete in two additional events – the asymmetric bars and the beam – to fill the gap left by Biles, while another team mate, Sunisa Lee, replaced her on the floor. And if they were subtly signalling that they had mixed feelings about Biles’s decision, they were hardly alone.

The withdrawal of a gymnast who has won some 30 Olympic and world championship medals has sparked a fierce debate over the impact that ‘mental health’ is having on sport.

While Biles’s supporters have hailed her for shining a spotlight on the issue, others have accused her of selfish and prima donna behaviour.

Some critics also point to the fact that Biles appears to be having her Olympic cake and eating it – deserting the team event and individual all-around finals but, as of last night, leaving it open that she might compete in the individual events next week.

Biles is going to ‘take things day by day’ before committing to compete in any of them. She intends to focus on her ‘wellbeing’, insisting that she pulled out so as not to jeopardise her team’s medal chances if she messed up again.

And it was ‘wow’ indeed as the 24-year-old superstar didn’t just walk away from the vault, but from the team event – in which she was captain – saying she wasn’t mentally prepared to compete and was battling ‘demons’

‘I just don’t trust myself as much as I used to,’ she added. ‘I don’t know if it’s age, but I’m a little bit more nervous when I do gymnastics. I feel like I’m also not having as much fun, and I know that this Olympic Games I wanted to do it for myself, and I was still doing it for other people, so that just hurts my heart badly, that doing what I love has been taken away.’

She is not the first elite athlete to cite mental health issues in the heat of competition. Naomi Osaka, the Japanese tennis star and ‘face of the Tokyo Games’ who lit the cauldron at the opening ceremony, pulled out of the French Open in May. She later revealed she was struggling with anxiety and depression. On Tuesday, she crashed out of the Olympic singles. Emotions, then, are running high at these games – when in February 2020, the Tokyo Olympics organisers unveiled the motto for the games as ‘United by Emotion’ they were spookily prescient.

US swimming champion and holder of eight Olympic golds Katie Ledecky yesterday wept after being beaten in the 200m freestyle. She said she had become emotional as she thought about her dead or ailing grandparents as she swam.

Ledecky expressed support for Biles, saying: ‘I would never want to speak for Simone, or say that I know what she’s feeling,’ she said, adding: ‘Certainly, Simone has so many eyes on her…the constant attention is not easy to handle.’ Sporting greatness is a ‘real blessing and a curse,’ she added.

In the case of Biles, those who argue that mental hardship deserves to be treated as seriously as physical injury in sport are now at loggerheads with opponents who insist that coping with the mental pressure comes with the territory at the very top.

Among that latter group of critics on social media yesterday were some who accused Biles of jumping on a ‘woke’ mental health bandwagon. This, they argued, was a clear cut case of an all-conquering gymnast – supremely self-confident in interviews and encouraged by a fawning media to believe in her invulnerability – finally meeting adversity and buckling. There have been claims that many other sports stars agree with this view but are scared of speaking out.

Few, however, can deny that Biles has had much to contend with recently in both her personal and sporting lives. Hailed as the ultimate all-American sporting rags to riches story, she was one of four children of an Ohio single mother, Shanon Biles, a jailbird with drug and alcohol problems. Biles was in and out of foster care until she was adopted in 2003 by her maternal grandfather and his wife, Ron and Nellie, who encouraged her gymnastics ambitions. Just 4ft 8in, she can jump twice her own height and has been described as flying through the air ‘as if she were part bird and part cannonball’. But despite her usual bubbly, energetic persona, Biles has already shown that she is vulnerable to the stresses of her sport. She sought the help of a sports psychologist after a poor performance in a major competition in 2013.

Three years later, it was revealed she took medication for attention deficit hyperactivity disorder. Then, in 2018, she revealed she had been among victims of Larry Nassar, a Team USA doctor who molested at least 150 female gymnasts. ‘I was very depressed,’ she said of the abuse. ‘It was a really dark time.’

Yesterday, Biles retweeted a supportive comment by former US gymnast Andrea Orris that read: ‘We are talking about the same girl who was molested by her team doctor throughout her entire childhood…That girl has endured more trauma by the age of 24 than most people will ever go through in a lifetime.’

A US team official said Orris’s message ‘sums up everything Simone is feeling and wants to say’.

At the height of her fame, Biles also had to cope with the trauma of her brother, Tevin, being accused of murder at a party he’d attended in Cleveland, Ohio. He was only acquitted of all charges last month.

American swim star Michael Phelps, with 28 medals the most successful Olympian of all time, has previously spoken out about the need to break down the ‘stigma’ of mental health in sport. Yesterday he said: ‘We are human, no one is perfect…I felt like I was carrying, like Simone said, the weight of the world on my shoulders.…I hope this is an eye-opening experience.’

It certainly has been. The influential US magazine, Sports Illustrated, claims the examples of Biles and Osaka signal a ‘new era of prioritising mental health’. Whether Russia and China, straining at the leash to push the US off the medal podiums, are quite so concerned about such matters is doubtful. Team USA – so used to winning – may have to get used to choosing between wellbeing…and gold.