It's fast, furious and threatens to present the Sochi Winter Olympics with its first major headache as the hunt for snowboarding gold is launched at the Rosa Khutor Extreme Park.

More than 240 athletes from 31 nations and regions were due to fly down the troubled track from Thursday, but that number has already been reduced by one after Norway's gold medal favorite in slopestyle, Torstein Horgmo, crashed in training and sustained a broken collarbone.

Fellow athletes complained aspects of the course were too dangerous, held an emergency meeting and forced officials into a rapid tweak of the most challenging aspects of the run.