Marielle Thompson underlined her status as favourite for the women's ski cross by taking Winter Olympics gold at Rosa Khutor Extreme Park.

The 21-year-old Canadian capped a fantastic season, that has seen her secure two wins and four podiums from seven World Cup races, by topping the standings in Sochi with a deserved victory, where she came first in all four of her races on Friday.

Compatriot Kelsey Serwa was on Thompson's heels for the entirety of the final but had to settle for silver, while Sweden's Anna Holmlund took bronze.

Ophelie David could not end her career with an Olympics medal after crashing midway through the course and finishing fourth.

France's David, world champion in 2007 and four times winner of the prestigious Winter X Games, was the oldest competitor in this event at 37 and had looked on course for a much-awaited Olympics podium, but stumbled over in the showpiece event.

Meanwhile, Anna Woerner and Stephanie Joffroy both had to be led away on stretchers in their respective quarter-finals in rainy and foggy conditions.

Germany's Woerner failed to complete the course after a high-speed crash and appeared to suffer a serious knee injury, while Joffroy of Chile also looked to have injured her leg after stumbling over in the very next heat.