Even in the absence of spectators at the Ariake Gymnastics Centre there was still a palpable tension when Simone Biles left the arena after finishing just one event in the women's team final on Tuesday.

An eager press tribune ready to witness the star attraction of these Games fell flat in concern when Biles, after one unconvincing performance on the vault which yielded the lowest score of the first rotation, headed to the back with a trainer while the team were involved in frantic discussions.

The warning signs had been there during the warm-up when Biles failed to complete an Amanar, a difficult vault but routine for someone of her immense talent. When it happened again in competition there was almost a stunned silence, Biles seemed to be nearing tears and her team-mates flabbergasted by what had transpired.

She would return but, donned in a tracksuit, it was announced Biles would take no further part and the team of Jordan Chiles, Sunisa Lee and Grace McCallum would complete the night for Team USA. The United States could only take silver, marking their first team defeat at a Worlds or Olympics since 2010.

USA Gymnastics later announced Biles had been pulled due to an unspecified "medical issue" and that her condition for the other five events she is scheduled to appear at will be "assessed daily", while NBC Sports attributed a Team USA coach with saying Biles' withdrawal was not injury related and due to a "mental issue she is having".

Biles had opened up on the pressures the Olympics brings following Sunday's qualifying, during which she made some uncharacteristic mistakes in an error-strewn team performance that saw USA outscored by the Russian Olympic Committee in what proved an eerie prelude.

"It wasn't an easy day or my best but I got through it," Biles posted.

"I truly do feel like I have the weight of the world on my shoulders at times. I know I brush it off and make it seem like pressure doesn't affect me, but damn sometimes it's hard hahaha!

"The Olympics is no joke. BUT I'm happy my family was able to be with me virtually. They mean the world to me."

The concerns over Biles' well-being will stretch far beyond the watching press pack at the arena. Those tuning in around the world will greatly hope this is not the way this megastar's Games come to an end.

Moreover, so will the organisers of the Games, who are desperately relying on the biggest stars to bring some positive PR to an Olympics many never wanted.

Having already had cauldron lighter Naomi Osaka, who returned to represent Japan after a self-imposed two-month hiatus during which she opened up about her battles with depression and anxiety, beaten in the third round of the women's tennis earlier in the day, to see Biles not compete would represent another hammer blow.

The IOC had earlier described its digital audience figures for Tokyo 2020 as "very good", but as the only way for fans to watch these Games is from the comfort of their own homes, you would kind of expect that to be the case.

If you want an idea of how important Biles is to these Games, consider that IOC president Thomas Bach was seen in conversation with the star attraction before congratulating the gold medallists. Biles herself had shown her textbook humility by being among the first to congratulate the victors in a moment of sheer class.

For these Olympics, held in the midst of a deadly pandemic, to actually be remembered for the right reasons, Tokyo 2020 needs to showcase the successes of athletes securing their crowning glories despite the unthinkable challenges posed for over a year and a half.

Such concerns are of course secondary to the welfare of a 24-year-old woman, who confirmed she is not injured, carrying so many hopes and pressures, whose delivery of the message "put mental health first" is as, if not more, inspiring than her brilliance on the floor.

This was the first of six gold-medal opportunities for Biles. Her stacked programme includes what many predicted to be a routine defence of her all-around crown, while she is slated to appear in the finals of the beam, uneven bars, vault and floor exercise.

She has designs on winning the most gymnastic gold medals at a single Games (she already owns the co-record with four following her haul at Rio 2016), while three more would see her overtake Shannon Miller as America's most decorated Olympic gymnast.

Biles later said she is "dealing with something internally" and that things would be taken day by day for the rest of the Games.

Speaking at a news conference, she would elaborate on the issues she has been contending with.

"It's been really stressful this Olympic Games on the whole, with no fans, it's been a long process, a long year, and lots of variable," she said. 

"We're all a little bit too stressed out, we should be enjoying ourselves.

"Today was really stressful, we had a workout this morning, it went okay then that five-and-a-half-hour wait I was shaking, I could barely nap. I've never felt that way before a competition."

That we all hope she will compete again at this Olympics goes without saying. 

But, perhaps save for Osaka, there is arguably no athlete more important to these Games. And, as Osaka has gone to great lengths to demonstrate this year, protection of mental health and well-being must come before all else.