The risks of this sport came into sharp focus in the women's contest when American Maddie Mastro, who is expected to challenge defending Olympic champion Chloe Kim in Beijing, landed hard on the decking and skidded to the bottom. She was bleeding below her left eye and taken off the mountain by sled. Contest officials said she suffered an ankle injury.

Kim, who already had her Olympic spot wrapped up, fell on her first two runs but came up big in her final trip down the pipe to eke out a one-point victory over Queralt Castellet of Spain.

"I'm never putting myself in that situation again. It was horrible," Kim said of the tension of a must-have final run. "I'm so glad I was able to land."

So was Hirano. "I was very happy to land the triple cork in competition for the first time," he said through an interpreter.

Whoever can pull it off at Beijing 2022 will be even happier. But in a sport that lives for progression, Hirano will always be able to say he did it first.

"Everybody would agree," Oetken said, "that we are pushing the limits of what is possible."

Agencies Via Xinhua