The Estonian, who won the halfpipe world title at the age of just 16 last year, captured slopestyle gold at the Winter Youth Olympic Games in Lausanne earlier this month.

She triumphed in Colorado today under a new scoring system which sees judges giving an "overall impression" instead of the best score from a single run being declared the winner.

"I didn't expect that today," said Sildaru to the Aspen Times. 

"I just tried to enjoy tonight and that happened. 

"So I'm really stoked."

Sildaru has won three slopestyle gold medals in Aspen and will now defend that title on the final day of the X Games tomorrow.

Two Canadians finished behind her in the superpipe, with Rachael Karker second and Olympic halfpipe champion Cassie Sharpe third.

History was made in the men's snowboard big air as the silver won by Canada's Mark McMorris saw him match the record of 18 Winter X Games medals held by American Shaun White.

The double Olympic bronze medallist was beaten by his team-mate Max Parrot, with Sweden's Sven Thorgren taking bronze.

Back-to-back Olympic gold medallist Jamie Anderson won the women's snowboard slopestyle for the United States, in front of Canada's Laurie Blouin and Japan's Kokomo Murase respectively.

Canada's Darcy Sharpe captured the men's snowboard slopestyle title, beating Norway's Mons Røisland into silver.

American Olympic champion Red Gerard took home bronze.

Colby Stevenson won the men's ski slopestyle title for the US, with Canada's Evan McEachran second and big air world champion Fabian Bösch of Switzerland third.

In the women's snowboard superpipe, Queralt Castellet grabbed gold for Spain.

Winter University Games halfpipe champion Kurumi Imai took silver for Japan and her compatriot Haruna Matsumoto won bronze.