Gu, 17, was skiing without poles due to a hand injury and had only qualified for the final in sixth, but a first-run score of 93.00 propelled the Chinese skier to the top of the leaderboard and there she would stay.

Featuring back-to-back 900-degree jumps to begin with, it turned out to be the winning run in Colorado.

Canada's Rachael Karker, who had been the best qualifier, overcame a slow start to take second place with a score of 91.75 in the final run of the competition.

That effort, which included back-to-back 900s as the second and third jumps, relegated Zoe Atkin of Britain to third.

Atkin's best score was 90.50.

"I definitely was really struggling on qualifier day and during training and that shook up my confidence a little, but dropping in today I was really feeling it, and Aspen Snowmass is always so amazing," Gu told the FIS website afterwards. 

"I’m just really excited to be here and really excited to show the world that I could come back and ski well."

Gu - a double gold medallist at both the Lausanne 2020 Youth Olympic Games and 2021 Winter X Games - will have another shot at a gold medal in the slopestyle, where she was the best qualifier.

Porteous, 19, like Gu completed an X Games superpipe-World Championships halfpipe double.

The New Zealander scored 94.50 on run one, buoyed by trademark back-to-back 1,620-degree jumps, and that proved to be the winning score.

Canada's Simon d'Artois came second on 91.25 and the United States' Birk Irving completed the podium with 89.75 points.

The ski slopestyle finals are scheduled tomorrow.