Coco Gauff, of the United States, returns a shot to Karolina Muchova (not in photograph), of the Czech Republic, during the women's singles semifinals of the US Open tennis championships, on Sept 7, 2023, in New York. (PHOTO / AP)

NEW YORK - American Coco Gauff beat Karolina Muchova 6-4 7-5 to reach her first US Open final on Thursday after the match was halted for nearly an hour when an environmental activist glued his feet to the floor of Arthur Ashe Stadium.

Gauff, who had beaten Muchova in the Cincinnati final last month to claim the biggest title of her career, fed off the energy of the home crowd to get past the Czech once again.

"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."

Gauff, the sixth seed, will next face the winner of the other semi-final between compatriot Madison Keys and Belarusian second seed Aryna Sabalenka.

Protesters disrupt the Women's Singles Semifinal match between Coco Gauff of the United States and Karolina Muchova of the Czech Republic on Day Eleven of the 2023 US Open at the USTA Billie Jean King National Tennis Center on Sept 07, 2023 in the Flushing neighborhood of the Queens borough of New York City. (PHOTO / AFP)

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

The USTA 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".

Gauff swept the first three games of the opening set and broke her opponent again in the sixth.

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Muchova, this year's Roland Garros runner-up, capitalized on some mistakes by the 19-year-old and broke straight back in the seventh, raising her level from there to break Gauff again in the ninth.

Karolina Muchova of the Czech Republic returns a shot against Coco Gauff (not in photograph) of the United States during their Women's Singles Semifinal match on Day Eleven of the 2023 US Open at the USTA Billie Jean King National Tennis Center on Sept 07, 2023 in the Flushing neighborhood of the Queens borough of New York City. (PHOTO / AFP)

The Czech's good work went to waste, however, as she committed a trio of unforced errors in the 10th game, allowing Gauff to break to love and take the set.

After a routine hold by Gauff to open the second set, shouts were heard from high up in the stands and both players sat on their benches as security staff members quickly moved to quell the disruption.

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.

Karolina Muchova (bottom), of the Czech Republic, returns a shot to Coco Gauff, of the United States, during the women's singles semifinals of the US Open tennis championships, on Sept 7, 2023, in New York. (PHOTO / AP)

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.

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Muchova gave credit to her opponent but told reporters that she was disappointed in the quality of her own play on Thursday.

"I was not feeling it from the start until the end," she said. "I'm pretty sad about the outcome, that I didn't put the best out of me on the court. Yeah, just kind of sad about the performance."