China's freeski star Gu recovers from crash to soar into Olympic big air final
Gu, who has not competed in the discipline since winning gold at the 2022 Beijing Games, was in a comfortable position after scoring 86.00 points in her first run of three.
But she fell on her second attempt, spending about 10 minutes talking to her mother at Livigno Snow Park and applying ice to her left wrist before returning to the top of the course.
That meant she was under huge pressure ahead of her final run but she punched the air in delight after she finished, scoring 84.75 for a combined total of 170.75, which meant she finished second.
Gu will resume her battle with Gremaud in Monday's final after the Swiss beat her into second place in slopestyle earlier in the Games.
Gremaud, who won big air bronze in Beijing, was third in qualifying with a score of 169.00.
Canada's Megan Oldham, who won bronze in slopestyle in Livigno, topped the charts with 171.75.
The top 12 competitors advanced to the women's final based on their two best runs of three.
US-born Gu, who switched allegiance to China in 2019, was one of the faces of the Beijing Games.
But she is out of practice in big air.
"Not only have I not competed in this event in four years, I also haven't trained for it," she said. "I'm just happy to be here."
The 22-year-old said tiredness may have been a factor in her fall.
"The nocturnal skiing is getting to me," Gu added. "Usually I sleep 10 hours a night and so getting home so late every night has been kind of getting to me.
"But more than that, I think it was just trusting myself, trusting my training, not changing too much in the contest."
Gu became the first athlete to secure three freestyle skiing medals at a single Winter Olympics in Beijing, winning half-pipe and big air gold and taking silver behind Gremaud in slopestyle.
The skier, who was the fourth highest-paid sportswoman in the world last year, according to Forbes, came to Italy hunting a clean sweep of titles.
Alongside her skiing, the multi-talented Gu studies at Stanford and models.
In big air, athletes ride down a slope towards a massive ramp, which they use to soar into the air and perform different aerial tricks.