On a tough night that saw the best riders struggle to stay upright, the toughest fall came from Ms. Kim’s toughest competition. Seventeen-year-old South Korean phenom Choi Ga-on had grown up looking to Ms. Kim as an idol. But Ms. Choi had fallen so hard on her first run they brought up a stretcher for her. (After a long time, she ended up not needing it). Then, on her second run, she fell again.