FLUSHING, N.Y. — Nobody settled into the U.S. Open women’s quarterfinal on Wednesday night expecting much of a surprise. The clean, flat hitting of the No. 6 seed Jessica Pegula is quite damaging to most opponents on tour, but it has not historically worked against top-ranked Iga Swiatek and her awesome wall of topspin. While Pegula managed to work her way into the lopsided matchup last season, winning two of their meetings, Swiatek still ended that year with a 6-0, 6-1 rout of Pegula that lasted 59 minutes and won her the WTA Finals. They hadn’t played since. Nothing about the way Swiatek has played on hard court this season suggested that she’d be blown out, 6-2, 6-4, unable to keep the ball in the court in a strange and uneasy matchup.

Aside from a brief struggle in the first round, it had been a businesslike U.S. Open for Swiatek: efficient dismissals of grossly overmatched foes and lower seeds alike. She’d navigated her service games with ease, getting in a healthy chunk of first serves, backing those up from the baseline, and facing zero break points in her last three matches. But Swiatek’s serve struggles took her out of contention in the first set. She got only a third of first serves into play, and double-faulted twice. Pegula broke serve twice to run up a 4-0 lead that proved insurmountable. Then the world No. 1 took the de rigueur, momentum-killing “bathroom” break. While a lot of players have used this strategy, it’s perhaps a bit more conspicuous coming from Swiatek, who has a wide range of tactics for slowing the pace of play. (Her usual is holding up a racquet to delay the server, which Danielle Collins memorably objected to at the Paris Olympics.) This occasionally grating control over match tempo is one way that Swiatek takes after her idol, Rafael Nadal.

A few minutes later, Swiatek arrived on court in a fresh all-white outfit; while there have been some catastrophically sweaty days at this tournament, Wednesday’s night session stayed comfortably below 70 degrees. My notes are littered with moments where it seemed as if Swiatek had made the necessary course-correcting adjustment, and was about to storm back. In reality, this never happened. Swiatek kept swinging big and kept spraying the ball long and wide, particularly on the forehand side.

Meanwhile, Pegula committed to a simple gameplan well-suited to her skillset: put flat pace down the middle of the court, play clean defense on the run to keep up the pressure, and force Swiatek to try and find her feel on the groundstrokes again. The top seed never met the challenge, nor did she ever land on a new plan of attack. After an ultimately fatal Pegula break of serve at 3-3 in the second set, Swiatek whacked the net with her racquet in an uncharacteristic outward display of frustration, and was also spotted weeping in the locker room afterward. In press, she praised Pegula for her “tricky ball because it’s pretty low and pretty flat,” and said the main reason she couldn’t get into the match was because of her serve struggles. While Swiatek initially rose to the top of the sport by streamlining her game into this more one-note, domineering style of play, she might benefit from restoring some other layers, as fall-back options when her preferred style goes awry.

The quarterfinal loss continues a mildly concerning trend for Swiatek. Even as she has continued to dominate Roland-Garros, winning four of the last five titles, she has struggled elsewhere. Swiatek hasn’t made the semifinal stage of any other major in the past two seasons, years she has largely spent as the No. 1 player in the world. Though Swiatek continues to crush the smaller tour events, her rival Aryna Sabalenka has developed greater consistency at the majors and can now be penciled into the semifinals whenever she’s in the draw. It’s worth asking whether Swiatek is managing her energy to peak at the most important moments in the year. She has spoken frequently this year about how exhausting she finds the new tour schedule, with its 10 mandatory 1000-level tournaments, but told press on Wednesday night that she plans to keep competing until November.

Swiatek’s exit is also a career peak for Pegula, who contributes to the anomalous American success at this U.S. Open, with four semifinalists across the men’s and women’s singles. This was Pegula’s first major semifinal berth after an 0-6 tally in her previous quarterfinals. In 2022, after being dispatched by Swiatek in the U.S. Open quarters, Pegula famously went to her press conference and cracked open a beer, partly to produce pee for a doping test and partly to “ease the loss.” She was the only current top-10 player in the WTA who had yet to appear in a major semifinal, and she erased that dubious distinction with a lopsided win over her most persistent bugbear. This tests the known limits of whether a fracking heiress can also be inspiring.