Gauff, at age 19, became the youngest American player to reach the final in New York since Serena Williams in 2001 after a protracted delay caused by protesters in the spectators.

These days, kids mature rapidly, and Coco Gauff is no exception.

In early July, she was a tentative tennis youngster probably heading into the sport’s wilderness, unable to explain why she was still waiting for her big moment despite having seemed so precocious and destined for greatness.

In September, she will be the focus of the media as a finalist at the U.S. Open, the country’s premier tennis competition.

On a sweltering Thursday night at Arthur Ashe Stadium, Gauff, a 19-year-old prodigy from sultry South Florida, defeated Karolina Muchova of the Czech Republic, 6-4, 7-5. Muchova’s all-court game and the oddest of atmospheres put her to the test like never before, but the night went her way in front of an audience that repeatedly erupted for her.

She added in her on-court interview, “Some of those points were so loud I don’t know if my ears are going to be OK.”

In the second set, with Gauff in command, a climate protest delayed play for nearly 50 minutes as the NYPD and security personnel struggled to remove protesters, one of whom had used an adhesive to glue his feet to the concrete in one of the upper levels of the stadium.

Gauff was up 6-4, 1-0, and playing excellently as the match was interrupted. Muchova, who was playing with a black compression sleeve covering her right arm from the biceps to the wrist and, she said, tape beneath the sleeve, appeared to be playing with a tight right arm.

While waiting for the game to start, Gauff and Muchova went to the locker room and the warm-up area to loosen up. Muchova relaxed with a massage and did some light jogging in the corridor outside the changing area. Gauff, who was acting erratically, walked up to a USTA employee and leaned over to look at photos of the demonstrators being shared online. She later revealed that when she woke up on Thursday, the thought of a climate protest breaking out immediately flooded her mind, as it had at the French Open in 2022 and at Wimbledon this year.

It’s possible you had a premonition. Maybe it was the work of a player who is known for always being well-prepared. She spent her entire high school career competing professionally, but she still managed to graduate on time in the spring of last year. They had a party in the City of Lights. She went on to win six matches at the French Open until losing in the final to the world’s number-one player, Iga Swiatek.

A year after witnessing Serena Williams’s final match, which marked the end of an era for American tennis, a capacity crowd of over 24,000 supporters arrived on Thursday ready to honor a new American tennis queen.

Gauff, who made her debut at Wimbledon when she was 15 and reached the quarterfinals of the French Open last year, has emerged as the frontrunner to fill the hole over the past four years. Since then, though, her development appeared to halt, especially on the biggest stages; she had not yet advanced past the U.S. Open quarterfinals, the tournament where the spotlight was brightest on her.

This run and a championship that is just one match away didn’t seem realistic two months ago, but Gauff showed Thursday night that there is every reason why there should be. She’s always possessed a lethal serve, a tough backhand, and the best court coverage in women’s tennis because of her lightning-fast feet and explosive athleticism.

She has spent the past five weeks mastering the usage of this equipment, and her once-unsteady forehand is now a formidable weapon. Against Muchova, she utilized both hammering and looping forehands, as well as slicing and hammering serves. She slashed with backhands and sprinted toward the net. She seized the initiative and battled with Muchova for points until the Czech star squandered them. Her feathery drop shot resulted in the first of her match points.

Gauff faltered in the middle of the opening set, dropping three games in a row after leading 5-1 as Muchova began to hit out and force Gauff backward. When serving for the match at 5-3 in the second set, she once again dropped her service.

It took three more games, one more break of Muchova’s serve, five more match points, an almost unending, lung-busting, 40-shot rally, strokes made within inches of the net, and moon balls that floated 10 feet above it before Muchova finally won. Then, she resisted Muchova’s final stinging serve and held on until her opponent’s final backhand volley went wide.

Since her first match in the tournament, New York has been hers; tonight, the finals berth was hers as well.