Chinese gymnast Shang Chunsong competes on the uneven bars during Sunday's qualifications at Rio's Olympic Arena. [Photo/Agencies]

Chinese gymnast Shang Chunsong was relieved she was able to play apart in qualifying on Sunday after illness almost caused her to miss the competition.

Shang has been recovering from a nasty bout of fever and wasn't able to train for nearly five days ahead of China's debut, a wobbly performance for a team hoping to regain the podium in Rio after relinquishing the gold medal to the US at the 2012 London Games.

Though far from perfect, China is well placed to reach Tuesday's team final, where a US contingent led by world all around champion Simone Biles is the favorite.

During her illness, Shang thought she might have to relinquish her spot on China's team.

"I was worried because the coach said that I might get replaced because I had a fever," said Shang, who is also expected to make the cut for the all around final.

She said the qualifying performance - where her vault was shaky and drew a low score of 12.766 - wasn't up to her standards and had been affected by nerves.

"I feel regret because I didn't perform well. If I performed more bravely, then I would have done better," Shang said.

Team China provisionally topped qualifying with a total of 175.279 points, but slid down the rankings after the world champion US squad scored 185.238.

None of the scores from Sunday carry over to Tuesday's team finals. In qualifying, four competitors from each country compete, with the top three scores counting toward the total. In the final, each nation has three athletes and all three scores will count.

It wasn't the first time Shang had overcome difficulty on her path to the Olympics.

Growing up in poverty in rural China, Shang's parents couldn't afford to hire a coach for her, and her visually impaired brother made a deep sacrifice. "My brother did a lot of things for me ... but we didn't have any money," said the 20-year-old.

"My brother gave up studying for me to do gymnastics. My dream is to find a way to cure my brother's eyes. I want him to see how beautiful the world is."