American teenager Coco Gauff shrugged off a 50-minute stoppage caused by climate protesters to power into the US Open final on Thursday with a straight sets defeat of Karolina Muchova.

The 19-year-old from Florida advanced to her first final at Flushing Meadows after winning 6-4, 7-5 in a semi-final that took nearly three hours to complete due to disruption by protests.

Gauff will face either second seed Aryna Sabalenka or compatriot Madison Keys in Saturday's final, who play later on Thursday.

Gauff later revealed she was expecting protests during the tournament, but said she remained unfazed by treating the interruption like a weather delay.

"I thought it'd be in the final, I just treated it like a rain delay," she told ESPN.

"In DC and Cincinnati people were passing out (because of the heat)... so I treated it like that."

The American youngster will be targeting her first Grand Slam title after battling to victory on the Arthur Ashe Stadium court.

Gauff, who is now the youngest American woman to reach the US Open final since her idol Serena Williams in 1999, had looked to be cruising towards victory in the first set.

The teenager broke Muchova twice early on to race into a 5-1 lead.

But her Czech opponent regained her composure and turned the tables as the fluency returned to her powerful groundstrokes.

Muchova fought back to break, cutting Gauff's lead to 5-4 after the teenager had twice served for the set.

However Muchova then faltered and Gauff broke back to clinch the first set when her rival hammered a backhand return into the net.

The second set was only one game old when environmental activists disrupted play, chanting "End fossil fuels". One of the protesters glued themselves to the floor of the stands, forcing a 50-minute stoppage.

When the players returned, a tense second set unfolded.

Muchova held off a match point in the 10th game to level at 5-5 before Gauff held for a 6-5 lead.

Muchova then saved four more match points on her serve before finally succumbing on the sixth match point, hammering a backhand return long to leave Gauff victorious.