Lindsey Vonn fell heavily during a women's alpine skiing World Cup super-G at Soldeu on Saturday and was evacuated on a ski-stretcher after lying prone for several minutes.
The American speed queen, who has a history of knee injuries sustained in competition, was in a battle with Switzerland's Lara Gut for the overall World Cup title and was 23 points clear at the start of the race.
She started well in poor visibility but failed to hold a corner in the latter stage of the course and crashed off the piste.
The race was interrupted for several minutes as assistance was sent to the American with Gut next in line to take the start.
Vonn was unable to stand and was taken away down the slope on a ski-stretcher to be taken to an Andorra hospital.
The race had been due to start in mid-morning, but was delayed for three hours because of the difficult conditions.
There was no immediate word on the extent of Vonn's injury.
Considered one of the greatest skiers of all time, Vonn has won Olympic and world titles in the speed disciplines during the course of her career and she has taken the overall World Cup crystal globe four times, the last being in 2012.
But she has been beset by knee injuries since then, missing most of the 2013 and 2014 seasons to undergo surgery.
But she had been back to near her best this year at the age of 31 and last month claimed her 76th World Cup victory, taking her closer to the overall record of 86 held by Sweden's Ingemar Stenmark.