Twan Van Gendt beat countryman Niek Kimmann of the Netherlands to win the men’s championship.
Willoughby went down hard in the second turn of her first run, but she bounced back to roll into the quarterfinals. The 2017 world champ advanced with U.S. teammate Felicia Stancil to the finals, where a perfect start out of the gate allowed her to edge Mulders by 0.445 seconds.
Axelle Etienne of France earned the bronze.
Van Gendt breezed to the men’s title with a run of 31.345 seconds. Kimmann was more than 4 seconds back in second, while French rider Sylvain Andre took third.