NEW YORK – Chris Evert says the subdued atmosphere at the U.S. Open has helped American Jennifer Brady make a lot of noise.

Brady. seeded 28th, notched the biggest victory yet in her breakout run at the Open, beating No. 23 seed Yulia Putintseva of Kazakhstan 6-3, 6-2 on Tuesday.

Brady said she was nervous at the start of her first Grand Slam quarterfinal. But with fans in the stands, Evert believes, Brady's jitters could have been worse.

"If you had 22,000 screaming fans, that might be a little bit of a disruption and a distraction for her," said Evert, a six-time U.S. Open champion and ESPN commentator. "Right now she's playing in her little bubble, she's only in her head, and that's producing her best tennis."

The 25-year-old Brady trained as a youngster at the Evert Tennis Academy in Florida. She is playing in her 13th Grand Slam event and is seeded in a major tournament for the first time. In the semifinals, she'll face two-time Grand Slam champion Naomi Osaka, who beat 93rd-ranked American Shelby Rogers 6-3, 6-4 in a quarterfinal match Tuesday.

Wednesday's women's quarterfinals are Serena Williams vs. Tsvetana Pironkova, and Victoria Azarenka vs. Elise Mertens.

Brady agreed it was easier to overcome her butterflies in the quarterfinal because there were no fans. She said she has struggled with doubt while climbing slowly through the ranks.

"I'm pretty lucky to have just stuck to it, and just really continue to just play and practice and compete and get better," she said. "Here I am today."

Relying on a powerful serve and forehand, Brady has lost only 24 games in five matches.

"She has matured," Evert said. "We had her at our academy when she was 10. She played like a guy, and I mean that in a good way. She had a lot of topspin; she moved so well; she had a lot of power; she had a kick serve when she was 12. ... She has come into her own right now."

With a win Thursday, Brady would become the first former collegiate player to reach the women's final at the Open since Billie Jean King made it in 1974. Brady played for 2014 NCAA champion UCLA, coached by Pete Sampras' sister, Stella Sampras Webster.

In the men's quarterfinals, Alexander Zverev won 14 of 15 points in a pivotal stretch on the way to earning his first semifinal berth at Flushing Meadows with a 1-6, 7-6 (5), 7-6 (1), 6-3 victory over Borna Coric.

It was a scratchy contest, with both men generating more unforced errors than winners through two sets, and Zverev finished with 12 double faults.

Next for the 23-year-old from Germany will be the winner of Tuesday night's quarterfinal between No. 12 Denis Shapovalov of Canada and No. 20 Pablo Carreno Busta of Spain.