This year marks her return to the competition, after missing the 2017 Open because she was pregnant with her daughter Olympia.
She also goes into the quarterfinals after winning against her sister Venus Williams on Friday. "This was my best match since I returned," Serena said, per ESPN, after beating Venus. "I worked for it. I worked really hard these last three or four months. That's life, you have to keep working hard, no matter ups or downs you have. That's what I've been doing."
Williams is going to take on former No. 1 Karolina Pliskova of the Czech Republic. Pliskova beat her during the 2016 U.S. Open in the semifinals. If Serena wins another singles championship, that will tie her with Margaret Court for the most Grand Slam singles titles ever, with 24.
The U.S. Open began Aug. 21 and will go on until Sept. 9. You can check out a schedule of Williams’ matches here.