Sunisa Lee says 'she's never been prouder' of her teammates after Simone Biles ...

When Simone Biles stepped back from the gymnastics team final in Tokyo on Tuesday, Sunisa Lee stepped up.

Lee, 18, along with teammates Jordan Chiles and Grace McCallum, won silver in the final behind Team USA's Russian rivals.

Now, she has taken to social media saying, she has 'never been prouder to be apart of such an amazing team with an amazing group of girls'.

'We stepped up when we needed to and did this for ourselves,' Lee wrote. 'We do not owe anyone a gold medal, we are WINNERS in our hearts.'  

When veteran captain Biles, 24, suffered a dramatic upset at the team final and suddenly withdrew from the competition after flubbing her vault, the remaining three members of Team USA — all first time Olympians — had to continue without her.

Lee was a standout in Tuesday's competition and arguably carried the team. She scored 15.400 on the uneven bars which is one of her strongest events.

Chiles, who replaced Biles on bars, delivered a strong performance, scoring 14.166 on bars and 14.666 on vault. Experts say she suffered in her floor routine, only scoring 11.700.

McCallum scored 14.300 on vault and 13.700 on bars. 

Lee also unveiled what is believed to be Team USA's nickname.

She posted a photo on Twitter of the girls with their silver medals with a caption reading: The Fighting 4.

Olympic nicknames are not uncommon, NBC reports, citing instances of The Magnificent Seven in 1996, The Fierce Five in 2012, and The Final Five in 2016. 

Biles has spoken out to praise the 'bravery' of her Olympic teammates and thanks them for 'stepping up when she couldn't'.

The 24-year-old cited her mental health struggles as the reason for her shock exit, said she made the decision to prioritize her own 'wellbeing' while insisting 'there is more to life than just gymnastics'.   

'It is very unfortunate that it has to happen at this stage because I definitely wanted this Olympics to go a little bit better but again, we'll take it one day at a time and we're going to see how the rest goes,' Biles told reporters.

The gymnast also insisted that her decision to pull out of the competition after just one event - when she was due to take part in all four - was made, in part, to help her team, saying that she 'didn't want to risk the team medal' with her 'screw up'. 

'I thought it was best that these girls took over the job which they absolutely did,' she continued, saying that the shock upset made them 'stronger' as a team. 'They are Olympic silver medalists now and they should be really proud of themselves now for how well they did last minute.' 

Meanwhile, three-time Olympic gold medalist Aly Raisman, who was the captain of both The Fierce Five and The Final Five, is criticizing USA Gymnastics and the US Olympic Committee for what she deems as lack of leadership and support for their athletes.

'USA Gymnastics has been an absolute disaster for years and unfortunately not enough has changed for us to believe in a safer future, but I think this just really shows the lack of leadership [of] USA Gymnastics and the United States Olympic Committee,' Raisman told CNN.

She argues that Biles' sudden exit from the final could be an indicator of a larger problem within the aforementioned organizations.

'Their best athlete is struggling ... is there someone there to help her?' said Raisman. 'I don't know. I'm not there, so I don't know. But I think it's an important question that we should be asking.' 

The Olympian, who cited her own experiences, acknowledged that being a star athlete in the global spotlight is 'a tremendous amount of pressure'.

'I'm completely devastated and I support [Biles] so much,' she added. 

Biles also received support from Athleta, the Gap-owned women's sports apparel company that also serves as one of Biles' sponsors.

'We stand by Simone and support her well-being both in and out of competition,' Athleta Chief Brand Officer Kyle Andrew said in a statement obtained by Fox Business. 'Being the best also means knowing how to take care of yourself. We are inspired by her leadership today and are behind her every step of the way.' 

It is currently unclear whether Biles will compete in the five individual event finals, which begin on Thursday with the all-around competition. 

Despite claiming a silver medal alongside her teammates, who were left on the verge of tears when Biles withdrew, the sporting superstar insisted the second-place finish had 'nothing to do with her' and gave full credit to Lee, Chiles and McCallum. 

'This medal is all of them and the coaches and nothing to do with me,' she said. 

Biles - who had been expected to lead the US to gold - was withdrawn from the lineup after flubbing her vault in the opening minutes of the team final competition in Tokyo on Tuesday, and it now remains unclear whether she will be fit to take part in the individual all-around this Thursday, with officials stating that she will have to undergo 'daily assessments' to determine her competition status. 

The gymnast admitted that she is 'dealing with some things internally', but seemingly vowed to return to competition in time for the all-around final, having gone into the Olympics as the favorite to win the gold. 

'I'm OK,' Biles said. 'Just dealing with some things internally which will get fixed out in the next couple of days.' 

When asked by the BBC whether she is planning to take part in the upcoming all-around final in two days, she replied simply: 'Yes.' 

However, when speaking to the Today show, Biles confessed that her determination to take part in the event - where she would be defending her championship title - is not enough to cement her place in the lineup, saying: 'We're going to take it day by day, and we're just going to see.'  

She went on: 'Physically, I feel good, I'm in shape. Emotionally, that kind of varies on the time and moment. Coming to the Olympics and being head star isn't an easy feat, so we're just trying to take it one day at a time and we'll see.' 

Opening up about her determination to prioritize her mental health Biles praised the other athletes — like tennis player Naomi Osaka who quit the French Open earlier this year, citing her own mental health struggles — who have spoken out about their own struggles, insisting that it has become a more important issue than ever, suggesting that sporting stars who are grappling with these kinds of issues are more likely to injure themselves during competition. 

'I have to focus on my mental health,' Biles said. 'I just think mental health is more prevalent in sports right now... we have to protect our minds and our bodies and not just go out and do what the world wants us to do.'

She admitted that her confidence has taken a serious knock as a result of her mental health issues, confessing: 'I don't trust myself as much anymore... maybe it's getting older. There were a couple of days when everybody tweets you and you feel the weight of the world. 

'We're not just athletes, we're people at the end of the day and sometimes you just have to step back. 'I didn't want to go out and do something stupid and get hurt. 'I feel like a lot of athletes speaking up has really helped. It's so big, it's the Olympic Games, at the end of the day we don't want to be carried out of there on a stretcher.

'You have to be there 100 percent or 120 percent or you're going to hurt yourself.'  

In a poignant twist, Biles' sensational exit from the team final came just hours after Osaka, who is representing her home nation of Japan at the Tokyo Games, crashed out of the Olympic competition in the third round in yet another dramatic upset.   

Speaking about the uncharacteristic error in a post-event press conference, Biles confessed that she felt as though she had 'robbed' her teammates of a fighting chance to claim the gold, saying: 'It's really unfortunate to have a score like that go up there for the team. I feel I robbed them… We could have been a little bit higher in the rankings. 

'I didn't do my job. They came out and they stepped up. They did what they needed to do.' 

In an Instagram post shared shortly after the team final came to a close, Biles once again praised her teammates for their performance, thanking them for 'fighting through adversity' and 'stepping up when she couldn't'. 

'I'm SO proud of these girls right here,' she wrote, while sharing an image of the four-woman squad proudly posing with their silver medals.

'You girls are incredibly brave & talented! I'll forever be inspired by your determination to not give up and to fight through adversity! 

'They stepped up when I couldn't. thanks for being there for me and having my back! forever love y'all.' 

She left the stadium with her trainer and was closely followed by medical staff - sparking fears that she had sustained a serious injury. Moments later, it was announced that she had been pulled out of Team USA's uneven bars lineup, and shortly after, it was revealed that she had been taken out of the competition altogether. 

Video captured the moment that the gymnast shared the news with her three teammates, telling them that she was 'sorry', but insisting that they were 'going to do great' because they had 'been training for this their whole lives'. 

'Look, you guys go out there and do what you're trained to do,' she told them. 'It is what it is. I'm sorry, I love you guys, but you're going to be just fine.' 

She then pulled each of her teammates into a hug, before reassuring them once again: 'You guys have trained your whole entire lives for this, it's fine. I've been to an Olympics, I'll be fine, this is your first. Go out there and kick a**, OK?'