Reigning Olympic ski cross champion Marielle Thompson may not get a chance to repeat at the PyeongChang Games after she suffered a serious knee injury during a training run this week in Saas Fee, Switzerland.

The world number No. 1 crashed after overshooting a jump, rupturing her anterior cruciate ligament (ACL) and medial collateral ligament (MCL).

The Whistler, B.C., native was subsequently flown to Vancouver for an MRI.

"It's definitely disappointing to hear the results [of the tests] after such a productive summer of training in the gym and on snow," Thompson said. "I'll be making a plan with my team moving forward and when the time is right getting back on the ski cross course stronger than ever."

Thompson, who won gold at the 2014 Sochi Winter Games, was a favourite to repeat in Pyeongchang.