What does it mean when we say a player has “tennis DNA”? If you’ve watched the sport long enough, you know it when you see it.

On an obvious level, it’s the ability to hit with effortless power, carve out a delicate drop shot, land a topspin lob on the baseline, and rifle a tweener. But it’s not just that. Good tennis genes can show up in subtler, less-spectacular ways. Such as knowing how and when to change speeds from shot to shot, without looking like you’re changing speeds from shot to shot. Or recognizing, instinctively, what your opponent will do next, and then holding your ground and creating a better response out of thin air. Or measuring your first passing shot so it just clears the net, and juicing the second one for a winner.

Linda Noskova, who did all of those things in her 4-6, 6-3, 6-4 upset win over Iga Swiatek on Saturday at the Australian Open, has tennis DNA. Few fans were probably aware of that before last night. Noskova is 19, she’s ranked 50th, and she hadn’t made it past the second round at a major before. Her claim to tennis fame was the 2021 Roland Garros girls’ title.

There’s a lot of tennis DNA in the Czech Republic, of course, particularly among the women. It goes back at least as far as net-rushing artists like Martina Navratilova and Hana Mandlikova, and continues today in the all-court games of Karolina Muchova and Barbora Krejcikova.

Noskova’s skills aren’t as eye-catching. At first, at 5’11”, with a strong build, big serve, and hard ground strokes, she can look like any other power-baseliner. And she more than held her own with Swiatek in that department. She hit 10 aces to Swiatek’s four, and 35 winners to the Pole’s 34. As Noskova says, “Obviously my game is to be aggressive almost all the time, especially at the right times.”

But she also won with her court sense. She read Swiatek’s approaches. She surprised her by suddenly shifting from safe rally balls to go-for-broke forehands. She absorbed Swiatek’s pace and turned it back on her. Just as important, even after losing the first to the WTA’s No. 1, she never looked as if she was just playing for a moral victory or a respectable score.

Down a break point at 3-3 in the second, with Swiatek surely thinking she was one swing from victory, Noskova surprised her by adding a couple of miles per hour to her second serve. She drew an error, and dug out the hold. Passing that test seemed to free Noakova up. In the next game, she broke Swiatek at love with a scintillating—and rare—inside-out forehand return winner.

For a lot of young players, that would have been enough for a night’s work in Laver, against this opponent. When Swiatek easily broke back to reach 2-2 in the third set, it looked like it might be. But again, Noskova played to win, and produced the superior tennis when she needed it. She broke at 3-3, fired two backhand winners to hold for 5-3, and came back from 0-30 down in the final game to hold for the win. Hitting an ace and a service winner on the last two points didn’t hurt.

“I mean, I just believed my game tonight,” said Noskova, who was making her debut in Rod Laver Arena. “I just really wanted this win because I didn’t really come to that court with the thought of, like, I have nothing to lose. I took it very seriously.”

“I just know that when I’m going to be aggressive, I can play with anyone.”