Coco Gauff knows what she is up against in her U.S.

Open semifinal against Elena Rybakina, whose firepower has vaulted her to the top of the tennis rankings.

“I know I'm going to have some aces hit on me and some winners hit on me, but I'm going to keep fighting and give it my all,” Gauff said.

“That's all I can do.” That's how Gauff earned her first title in Flushing Meadows and why she's still in the running for another.

U.S.

Open: No.

1 Zverev enters semifinals with ease; to face Khachanov Gauff fought off a couple match points in a tiebreaker and beat Mirra Andreeva 2-6, 7-6 (7), 6-2 on Wednesday to set up matchup against the new No.

1 in women's tennis.

Gauff overcame a horrible start to give herself a chance at a second U.S.

Open trophy.

She won the tournament in 2023, when she had to shake off a similar rough beginning against Aryna Sabalenka in the final.

Andreeva, the French Open champion, won the first seven points and took the first set in 26 minutes before the No.

4-seeded Gauff regrouped.

She said during the break after the first set she thought about fellow American Frances Tiafoe, who came from two sets down in his quarterfinal match a day earlier.

“So, honestly I was just trying to literally leave the court with no regrets,” Gauff said.

Elena Rybakina, of Kazakhstan, celebrates winning a match against Qinwen Zheng, of China, during the quarterfinal round of the U.S.

Open tennis championships | Photo Rybakina edged Zheng Qinwen 3-6, 6-1, 6-4 earlier Wednesday, guaranteeing she will become No.

1 in the WTA rankings after the tournament.

The top-ranked Sabalenka faces No.

3 Jessica Pegula in the other semifinal Thursday.

But no matter what happens in the remaining matches, Rybakina will end Sabalenka's 99-week stay at No.

1 when the new rankings are released Monday.

“It's just a number right now and of course I'm in the semis so my goal is to win the tournament,” Rybakina said.

“It's an amazing achievement but you know how quick everything can change in tennis, ranking-wise, during the match, so I feel like I just need to focus on my game, try to recover and enjoy tomorrow.” It's the first time since 1975 that all four of the women's top seeds reached the U.S.

Open semifinals.

Gauff won a 39-shot rally to take a 5-3 lead in the tiebreaker, but Andreeva took the next three points to earn her first match point.

Gauff erased that when the Russian sent a forehand long, then stopped Andreeva's second chance at 7-6.

Then it was mostly all Gauff in the third set en route to her seventh Grand Slam semifinal.

Rybakina struggles with an early start after the US Open's latest finish Rybakina and Zheng were scheduled to start about eight hours after Ben Shelton finished off his victory over defending champion Carlos Alcaraz at 3:33 a.m., the latest finish in U.S.

Open history.

Rybakina said she struggled with the sun and shadows in Arthur Ashe Stadium early on after starting later in the day in her previous matches.

Zheng capitalized on Rybakina's early struggles to get her only break of the match against one of the best servers in women's tennis and take a 5-3 lead in the first set.

But Zheng, who had been playing from behind so much in Flushing Meadows, couldn't hold onto the lead and Rybakina rolled through the second set in 38 minutes.

Zheng, the 2024 Olympic gold medalist from China, had to come through the qualifying tournament just to make the main draw after elbow surgery dropped her down the rankings to her current place of No.

121.

Once ranked No.

4, she is guaranteed to move back into the top 60.

She made a dramatic run to the quarterfinals, erasing a 5-0 deficit in the third set against Madison Keys in the third round and then climbing out of another 5-0 hole in the first set in her fourth-round victory over No.

8-seed Iga Swiatek.

But a double-fault gave her opponent a 5-4 lead in the third set and Rybakina served it out to reach the U.S.

Open semifinals for the first time.

“I think the wins that I had so far are great, but obviously today in the match I got a lot of chances in the third set, but I didn't take it,” Zheng said.

“That was a bit pity for me to lose this match, but obviously I could take positive things from U.S.

Open this year.” Rybakina came into the tournament needing only to reach the semifinals to ensure she would move past Sabalenka.

Had the 27-year-old from Kazakhstan lost before the final four, Sabalenka, Pegula or Gauff could have been No.

1 next week by winning the tournament.

Setting up the men's semifinals Karen Khachanov reached his third Grand Slam semifinal when No.

28 seed Alexander Blockx stopped playing midway through the third set after Khachanov had won the first two.

Blockx had his upper left leg wrapped and received treatment on both his lower leg and back as well.

Khachanov, who reached the semis at the U.S.

Open in 2022 and the 2023 Australian Open, will play top-seeded Alexander Zverev in one semifinal match Friday.

Shelton and Tiafoe will square off in an all-American semifinal match.