The women weren’t spared from the shock.

At the conclusion of a chaotic day when four of the top 10 seeds were eliminated from the U.S. Open men’s draw, 2017 champion Sloane Stephens, the 11th seed, was upset by 20-year-old qualifier Anna Kalinskaya, 6-3, 6-4, under the lights Tuesday at Arthur Ashe Stadium.

Kalinskaya, the 127th-ranked player in the world, won a Grand Slam match for the first time. She advanced to the second round, where she will face New Jersey native Kristie Ahn, who achieved the same feat hours earlier.

In 2017, Stephens became the first American other than Serena or Venus Williams to win a Grand Slam in nearly 16 years, since Jennifer Capriati won the Australian Open, and the first in 19 years, since Lindsay Davenport, to win the U.S. Open. The Florida native subsequently has lost three times in the first round of a Grand Slam. Stephens, 26, had appeared in the main draw of the U.S. Open on seven other occasions, previously only losing in the first round in 2015.

“It’s disappointing,” Stephens said. “I’m just going to have to keep working to get back to where I want to be, feel how I want to feel on the court.”

Stephens came to Queens struggling in the hard-court season, and ended her partnership with coach Sven Groeneveld eight days before Tuesday’s match. She then reunited with Kamau Murray, who coached her from 2015 through 2018.

“Obviously it’s going to take more than five days, or whatever, to get it back,” Stephens said. “I was joking earlier today I need to practice my fist pump because I’ve been so out of it, the competitiveness hasn’t been there.”

Going up against someone who had been bounced in the first round of her only four Grand Slam appearances, Stephens somehow looked unprepared for the moment, committing 33 unforced errors, while Kalinskaya countered with 15.

At 4-4 in the second set, Kalinskaya went up a break after Stephens committed three straight unforced errors. Stephens then saved a pair of match points, but ended the night watching the young Russian drill a backhand winner down the line.

“I didn’t play my best,” Stephens said. “Sometimes it happens.”