When main-draw singles play at the U.S. Open began, on Monday, there were, among the thirty-two seeded women’s players, four from the Czech Republic. There were also four American women—no other nation had more than that—but the population of the Czech Republic is about three per cent that of the United States. For that matter, it’s only half that of Florida, where most Americans on the women’s tour live or train. The top-ranked women’s doubles player in the world, Barbora Strýcová, is also Czech—in fact, there are three Czech women in the doubles top ten.

Why are there, in this era, so many terrific Czech players in women’s tennis? There is no simple answer; there may not even be an elaborate, nuanced answer. Maybe it has to do with the parents of these players coming of age in the nineteen-seventies and eighties, during the heyday of Martina Navratilova, who was born in Prague and grew up in Řevnice. Maybe, in the years after the Velvet Revolution, in 1989, and the freeing up of Czech broadcasting, it was the inspirational presence on TV of Helena Suková, who won doubles championships at each of the four Grand Slam tournaments, and Jana Novotná, who reached No. 2 in the world in singles and won Wimbledon, in 1998—although the women in the game today were only small children back then. Maybe, as some of the players have suggested, it’s the support system for junior players or the coaching—although it’s not clear why this wouldn’t be helping the men; with the aging and fading of Tomáš Berdych, there is no longer a Czech men’s player within shouting distance of the top fifty. (Perhaps the men are all playing soccer and hockey now.)

Karolína Muchová lacks the powerful serve of her countrywoman Karolína Plíšková—though she defeated Plíšková, a perennial top-five presence, at Wimbledon, last month, in as good a match as there’s been this year in women’s tennis. She does not have the commanding groundstrokes of Petra Kvitová, another top Czech, who was upset on Thursday in the second-round by Andrea Petkovic, of Germany. Muchová, who turned twenty-three last week, is among the younger cohort of élite Czech players, which also includes the twenty-year-old Markéta Vondroušová, who reached the French Open final, in June. (Vondroušová withdrew from the U.S. Open last week, citing a wrist injury.) What she has is the kind of all-court game, with changes of pace and spin and shape to the struck ball, that has emerged, this year, as the way that the next generation of women is playing.

On Thursday afternoon, Muchová’s faced Hsieh Su-wei, of Taiwan. The match was out on Court 4, at the edge of the tennis grounds at Flushing Meadows; from the sun-spangled bleachers, the fans could, between points, watch the traffic on the Grand Central Parkway. Hsieh, a veteran in her thirties, hits from both wings with all kinds of spin. She never approaches a ball she wants to hit squarely. She is a longtime and deft practitioner of what might be described as a rococo heightening of all-court style.

In just twenty minutes, Muchová rushed out to a one-set lead—less on the strengths of her game than on the weakness of Hsieh’s serving, a liability that can flare up from time to time. Things settled down a bit in the second set, although with their scurrying for lobs and drop shots, the play never rose to cool point construction or rally-ball forehand exchanges. Muchová, like Plišková and Kvitová, waits just an instant longer to let swing her two-handed backhand than most players are coached to do; she makes contact with the incoming ball not in front of her but almost to the side. This technique causes her to lose some pace on the shot, but it also makes it harder for an opponent to see where she’s directing the shot. On Thursday, however, the lack of pace on Hsieh’s shots was giving Muchová too much time to think, which seemed to throw her off; she dropped the second set sloppily, forcing a deciding third set.

When the third set began, Muchová was immediately committed to meeting Hsieh’s gossamer slices at the net—she came forward more than twenty times. A stiff breeze was blowing the service tosses of both players off-course, and there were backhand unforced errors and netted first serves from both players. But Muchová’s chipping and charging were exceptional, and it won her the match, 6–1, 4–6, 7–6 (2).

Afterward, when Muchová was taking questions from reporters, I tried to draw her out about why Czech women are having so much success on the tour. She smiled in a way that was equivalent to a roll of her eyes: she’s been asked that question before, she said, and she has no explanation. She was not thinking about the Czech Republic but about Arthur Ashe Stadium, where she would be playing her third-round match the very next day. It would be her first time playing on that court, and her first time facing her upcoming opponent—Serena Williams. She was going to need some rest.