Joss Christensen led the way with gold as the United States claimed a clean sweep of medals in the first ever Winter Olympics men's ski slopestyle final.

Christensen topped qualifying with two scores over 90 and went on to better that in the final, with a 95.80 enough to edge him ahead of more established duo Gus Kenworthy and Nick Goepper, who settled for bronze and silver respectively on the sun softened Rosa Khutor Extreme Park.

Christensen's run was almost perfect, with clean landings and a finish of a switch triple-corked 1440, and even though he had sealed top spot the 22-year-old put down a run of 93.80, which would have been enough for gold.

''I can't really believe it right now, this is pretty crazy. It has been just an amazing day,'' said the little-known Christensen, who was only awarded a spot on the Olympics team after winning a qualifying event last month.

Poland's Justina Kowalczyk dominated in the cross-country women's 10km classic to take gold.

The 31-year-old, who won gold over 30km in Vancouver, led at every time-split over the course and finished 18.4 seconds ahead of defending champion Charlotte Kalla, who took her second silver of the Games following second place in Saturday's skiathlon.

Norway's Therese Johaug, the world champion over 10km, improved on her fourth place in the skiathlon to take bronze, a further 9.9 secs back.

China's Li Jianrou escaped a crash to win a dramatic women's 500 metres short track final in the Iceberg Skating Palace.

After a false start by Korea's Park Seung-Hi, Britain's Elise Christie made a flying start but then appeared to cut across the line of Italy's Arianna Fontana, taking both of them out.

Fontana's fall also took down Park, leaving Li to skate away unopposed to the gold medal.

Park and Christie picked themselves up and the 23-year-old Scot, whose speciality is the 1000 metres, overtook Park to cross the line second but, inevitably, she was disqualified by the judges, leaving Montana second and the Korean third.

Lizzy Yarnold is firmly on course for skeleton gold after Thursday's opening two runs saw her build a lead of almost half a second over American arch rival Noelle Pikus-Pace.

Britain's gold medal favourite justified that billing with runs of 58.43 seconds - a course record - and 58.46secs to carry a 0.44secs advantage over Pikus-Pace into Friday's final two runs at the Sanki Sliding Center.

Russian challenger Elena Nikitina was only 0.05secs adrift after the first runs but lost time in the lower part of her second run and is 0.55secs adrift of Yarnold at the halfway stage.

Canada made it four wins from four in the women's curling round-robin stage, beating Denmark 8-5. Defending champions Sweden were 9-8 victors over previously-unbeaten Switzerland, while Great Britain edged China 8-7.

Finland began their challenge in the men's ice hockey with a 8-4 thumping of Austria, and Germany saw off Japan 4-0 in the women's event.