Watch: Kiwi teen Zoi Sadowski-Synott adds gold, in dramatic fashion, to X Games haul

Kiwi snowboarder Zoi Sadowski-Synott has claimed a dramatic gold medal in the slopestyle event at the X Games, added to the field on the morning of the event in Aspen, Colorado.

Having already won silver in the snowboard big air competition on Friday, the 17-year old was named as an alternative for this morning's slopestyle, eventually given the green light to compete.

The young Kiwi was up second, earning back to back 900s, before a double wildcat secured her 90 points out of a possible 100.

With a hold on the top spot, Sadowski-Synott went even better on her third run, scoring 91 to take the gold.

"Words can't even describe how I'm feeling," she said.

"I woke up this morning not even expecting to ride today and then I managed to land a run I hadn't done before in competition. I'm just really happy."

The USA's Hailey Langland finished in the silver medal spot, coming close to beating the Kiwi with a 90.66 on her final run. Finnish athlete Enni Rukajarvi was third.