Switzerland's Marco Odermatt overcame snow and fog to win giant slalom gold at the Beijing 2022 Winter Olympics Sunday, while sport's top court was to decide if 15-year-old Russian figure skater Kamila Valieva can compete at the event.

The buildup to the Games in the Chinese capital was dogged by concerns about COVID-19 and human rights and has now passed the halfway point with yet more controversy surrounding them.

This time it involves skating sensation Valieva, whose Games hang in the balance after it emerged that she tested positive before the Olympics for a banned substance.

The Court of Arbitration for Sport (CAS) was to hold a video hearing before delivering its verdict Monday, just a day before Valieva is scheduled to compete in the women's singles competition, one of the most closely watched events at the Olympics.

Valieva was a strong favorite for gold but her Olympics and her fledgling career are now in jeopardy.

Christophe Dubi, Olympic Games executive director, said it was important to remember the "human side of this story ... to think about a person of 15 in this situation."

"We need to treat this situation extremely carefully," said Dubi.

Valieva, who became the first woman ever to land a quadruple jump in an Olympic competition as Russia won team gold Monday, tested positive for trimetazidine after competing at an event in Saint Petersburg on Dec. 25.

However, the International Testing Agency says the World Anti-Doping Agency-accredited laboratory in Stockholm only reported that Valieva had returned a positive case on Feb. 8 – the day after she won team gold in Beijing.

The Russian team and the government have raised questions about why it took six weeks for the result to come out.

Valieva again practiced Sunday, watched by her coach Eteri Tutberidze, who has herself come under scrutiny in the wake of the affair.

The teenager declined to comment to reporters afterward but appeared in good spirits, laughing and joking with members of the Russian coaching team.

The case is just the latest doping scandal surrounding Russian athletes at the recent Olympic Games, which led to a two-year ban.

Russian competitors are taking part in Beijing under the flag of the Russian Olympic Committee (ROC), providing they have been able to prove they were not tainted by a massive state-sponsored doping program focused on the 2014 Sochi Olympics.

The Russian flag cannot be displayed at the Games and the national anthem cannot be played.

Odermatt wins in the snow

Heavy snow fell Sunday but Odermatt lived up to expectations by holding his nerve to win the men's giant slalom.

Odermatt, who finished seventh in the downhill and skied out of the super-G, clocked a combined total of 2 minutes 09.35 seconds over the two legs down the "Ice River" course, where snow and fog made conditions tricky and visibility poor.

Slovenia's Zan Kranjec claimed silver, 0.19 seconds off the pace while reigning world champion Mathieu Faivre of France took bronze, 1.34 seconds behind the winner.

"It was a hard day with the conditions, with such a long wait between the two runs," said Odermatt, who estimated it was five hours between his first and second runs.

These Olympics are being held on mostly manmade snow because Beijing is one of the driest parts of China.

However, snow tumbled steadily throughout the day in the capital and in the mountains outside Beijing where skiing, snowboarding and sliding events are taking place. The snow was forecast to ease up by Monday morning.

The weather forced the postponement of qualification in the women's freestyle skiing slopestyle, in which Californian-born Chinese sensation Eileen Gu is going for a second gold medal.

The qualification round of the event will now take place on Monday.

Norway's Marte Olsbu Roeiseland won the women's 10km pursuit in biathlon and in cross-country skiing the Russians took gold in the men's 4x10-kilometer relay.

These Games are over though for Slovakia's newly crowned slalom champion Petra Vlhova, who has picked up an injury.