Jessica Pegula reached her first Grand Slam singles final after coming back from a set down to defeat Karolina Muchova 1-6, 6-4, 6-2 in their stunning semifinal match late on Thursday night,.

Pegula, at 30 years old, is the oldest Grand Slam final debutante at the US Open since Flavia Pennetta reached that stage in 2015. She is the third American woman aged 30 or over to make a US Open final, joining Serena Williams and Martina Navratilova.

She is the fourth player in the Open Era to reach the finals in Canada, Cincinnati, and US Open in a season, joining Rosie Casals (1970), Evonne Goolagong Cawley (1973) and Serena Williams (2013). This is the first time an American man and woman have reached the singles finals at a Grand Slam since 2002, according to WTA stats.

Pegula, who defeated world No.1 Iga Swiatek in the quarterfinals, will face World No.2 Aryna Sabalenka for the US Open title on Saturday. The match is a rematch of last month’s Cincinnati Open final, which Sabalenka won 6-3, 7-5.

Muchova saved three break points in her second service game and then displayed her impressive all-court game, mixing slices, serves, and volleys. Pegula couldn’t find answers, losing her serve after the first changeover. Muchova dominated, winning 16 of the final 20 points, including all seven at the net, to claim the first set in just 28 minutes.

In the second set, Pegula fought back after Muchova’s early 2-0 lead. Pegula found her rhythm, hitting with more authority, and leveled the score by forcing errors. She then earned four break chances with Muchova serving at 2-3.

Muchova showcased her remarkable shotmaking to save several break points, but couldn’t hold off the fourth. The break advantage would prove short-lived, but the shift of momentum gave the American confidence. She gained early leads in the next two service games and converted a set point at 4-5 after a double fault from Muchova, claiming the second set.

The third set started as a reversal of the second, with Pegula breaking early thanks to powerful deep returns. Muchova fought back in nearly every service game, overcoming 40-0 deficits.

At 4-2, Muchova had her best chance to level the final set during a lengthy game with multiple deuces. However, she missed a crucial slice on break point. Pegula capitalised, extending her lead to 5-2 and then broke again to secure her first-ever Grand Slam final spot.

The American is bidding to match compatriot Coco Gauff’s path to her maiden Grand Slam title one year ago in New York. Gauff beat Muchova in last year’s semis before coming from a set down to beat Sabalenka in the title match.