Two American women will play on Thursday for spots in the U.S. Open final.

One, Coco Gauff, the No. 6 seed, will play in the semifinals against 10th-seeded Karolina Muchova of the Czech Republic. On the other side of the draw, 17th-seeded Madison Keys of the United States will face off against second-seeded Aryna Sabalenka of Belarus, this year’s Australian Open champion.

Much of the spotlight in this tournament has been on Gauff, 19, in part for how far she has advanced on the tour while still a teenager. She reached the French Open final last year, and she is the first American teenager to reach the U.S. Open semifinals since Serena Williams did it in 2001.

To reach the final, Gauff will need to defeat Muchova, who reached the French Open final this year.

Here’s what to know about the match between Gauff and Muchova, set for Thursday at 7 p.m., Eastern time.

How did they get here?

Muchova has effectively cruised into the semifinals. Through her first five matches, she has dropped only one set, which came in the fourth round against Wang Xinyu. She advanced to the semifinals after defeating Sorana Cirstea, 6-0, 6-3, in the quarterfinals.

Some of Gauff’s matches have gone on longer than she would have liked. She played a full three sets in the first round against Laura Siegemund, in the third round against Elise Mertens and in the fourth round against Caroline Wozniacki. In the quarterfinals, Gauff defeated Jelena Ostapenko, 6-0, 6-2, in just over an hour.

Gauff says she’s feeling fresh.

Gauff has spent a lot of time on court this tournament. In the single’s draw alone, she has played 9 hours 19 minutes. She has also played four matches through the quarterfinals in the women’s doubles draw with her partner, Jessica Pegula. She also played one match in the mixed doubles draw with Jack Sock.

But despite all the court time, Gauff said after her victory over Ostapenko that she has been working to build her endurance for the later stages of Grand Slam tournaments.

“I’m still in the mind-set that I’m in the beginning of the tournament,” Gauff said. “I just feel so fresh, to be honest. I don’t know if it’s because I’ve been tricking myself or maybe when this is over I’m going to hit a wall. But I’m really proud of how I’m able to get through these matches.”

Gauff beat Muchova recently.

Gauff and Muchova have played each other only once. That match was in August in the final of the Western & Southern Open in Ohio, which Gauff won, 6-3, 6-4.

Gauff said she was going to plan a different approach to playing Muchova this time because she thought Muchova was struggling physically in that match.

“I don’t think that will be the case again,” Gauff said.

Muchova didn’t want to reveal too much about her tactics against Gauff in the semifinal, saying she would focus on her own game. But Muchova said she knows Gauff has several tools to use in matches.

“She’s very athletic,” Muchova said. “She never gives up, runs for every ball, doesn’t do many mistakes. She has kind of all the strokes.”

Both players have reached a Grand Slam final.

Now they want to win one. Muchova reached the final of the French Open this year, but lost in three sets to Iga Swiatek. Gauff experienced the same thing last year at the French Open, where she also lost the final to Swiatek.

But while experience in a Grand Slam final is important, Muchova will also face a loud crowd that will be eager to cheer for an American in Arthur Ashe Stadium on Thursday night.

Aryna Sabalenka or Madison Keys will be next.

The winner of the Gauff-Muchova match will play the winner of the other semifinal matchup, between Sabalenka and Keys, which follows. Sabalenka is favored to win, but, like Gauff, Keys will have an American crowd backing her in Arthur Ashe.

“Of course, they will support her more than me,” Sabalenka said of Keys on Wednesday. “I’ll just try to stay focused and try to play my best tennis.”

The women’s final is scheduled for Saturday at 4 p.m.