Eileen Gu amassed an army of cynics when she spurned Team USA to represent China at the Beijing Games.

Moments after the biggest run of her life, the 18-year-old freestyle skiing prodigy was asked about her status as a US citizen, her feelings on Peng Shuai and the incessant hate she has received on social media.

"If people don't believe me, if people don't like me, then that's their loss," Gu said.

"They're never going to win the Olympics."

Gu did just that, earning the first of what she and her many fans in Beijing hope could be three gold medals by cranking out the first 1620 of her career in her final turn, stunning Tess Ledeux of France to win the Olympic debut of women's big air.

The American-born Gu had never landed the double cork 1620 — a move in which skiers spin four-and-a-half times while rotating twice off-axis while 6 metres in the air.

"I want all the girls to break their boundaries," she said in Chinese, via an interpreter.

"I want them to think if Eileen can do it, I can do it."

A flood of interest in Gu's win briefly crashed the popular Chinese social media site Weibo, according to online technology and sports news sites in China.

A crowd of spectators gathered spontaneously in front of a big TV screen in Wangfujing, a famed shopping district in central Beijing, on Tuesday morning.

Sina Weibo, the massive social network that is similar to Twitter, found its servers temporarily overloaded, according to Chinese media.

Of the top 10 trending topics on the platform, five were dedicated to adoration for the 18-year-old champion.

"Gu Ailing is a genius young woman right?" was one trending topic, referencing her Chinese name.

"Dad was Harvard, Mom was Peking University, Stanford, Grandmother was an athlete. She's beautiful and classy," said one post recirculated 86,000 times.

It was a stark contrast to the reception received by another US-born athlete competing for China.

Figure skater Zhu Yi came under attack earlier in the Games on social media after she crashed into a wall during the team event.

Zhu finished last in the short program and China placed fifth in the competition, which was won by the Russian team, with the US taking silver and Japan bronze.

Weibo said it had suspended 93 accounts and deleted 300 abusive posts about the Olympian, who was born in California to Chinese parents and won a US national novice title as Beverly Zhu.

Messages mocked her for falling while others criticised her for not being fluent in Chinese.

"There's no next time," wrote one Weibo user, under a video of Zhu crying at the end of her performance. "How shameful."

That comment was liked more than 45,000 times.

"Go back to America," read another comment accompanied by a US flag emoji.

The anger toward Zhu was likely fuelled by an episode a few weeks earlier when she qualified to compete at the Olympics.

She beat out two other skaters for the last spot on the Chinese team, which many fans felt should have gone to another young skater, Chen Hongyi, who had more competitive experience.

It caused enough of a controversy at the time that the Chinese figure skating Olympic selection committee issued a statement defending the decision.

As online criticism of Zhu crested, Gu came to the defence of her teammate.

"Making mistakes and pressure are all part of sports," Gu said at a news conference after her victory.

The two athletes are competing at a politically fraught moment, with a foot in each of two countries that have been clashing on a variety of issues, from economics to the lock-up of China's ethnic Uyghur minority population in the western Xinjiang region to the origins of the COVID-19 pandemic.

AP