Aryna Sabalenka of Belarus recovered from a 0-6 opening loss to reach the U.S Open women's singles final against local Madison Keys on Friday, setting up the showdown with home favorite Coco Gauff who dispatched Czech Karolina Muchova 6-4, 7-5 earlier. 

As a massive home crowd were ready to celebrate a potential all-American final they hoped for when Keys bageled the incoming world No.1 in the opening set and was 5-3 up in the second, Sabalenka started her comeback.

She broke for the first time in the match to get back to 5-4, and went to a tie-break which she won 7-1, sending the contest to a third set that minutes earlier no one saw coming.

With the tension rising so did the quality of the match, the players traded breaks in a tight third set that came down to a super tie-breaker which Sabalenka again dominated 10-5.

"It really means a lot to be in the final of the U.S. Open for the first time," said Sabalenka, who rode an emotional rollercoaster, angrily remonstrating with her coaching team at times, before being able to sheepishly laugh off celebrating prematurely in the decisive tie-break.

"I thought that we play tie-break up to till seven," she said. "I was just all over the place."

The Australian Open champion has a 3-2 edge against Gauff, but this will be their first meeting at a major.

"She's an unbelievable player," Sabalenka said of Gauff. "The crowd will be supporting her a lot. I will do everything I can. I'll be fighting for every point and I will do my best."

Earlier, Gauff downed the tenth seed in a repeat of last month's Cincinnati final when she won her first WTA 500 singles title.

"Some of those points, it was so loud and I don't know if my ears are going to be okay," Gauff said. "I grew up watching this tournament so much so it means a lot to me to be in the final. A lot to celebrate but the job is not done."

The match was delayed by roughly 50 minutes early in the second set due to a protest by four spectators.

The United States Tennis Association said three of the four were escorted out of the stadium without incident but a fourth "affixed their bare feet to the floor of the seating bowl".

As the delay stretched on both players left the court as police officers surrounded the remaining protester before removing him from the venue with his hands behind his back.

After the players returned they warmed up again on court before resuming play, neither appearing rattled by the incident.

Muchova double-faulted to help Gauff break in the eighth game but saved match point in the next game before breaking the American's serve to keep the match going.

Muchova saved four more match points in the 12th game but Gauff would not be denied, surviving a 40-shot rally on the penultimate point with a forehand winner before cheering with delight as her opponent sent a backhand past the baseline on the sixth match point.

(With input from agencies)