Vondrousova went into the match with an 0-5 record against Top 10 players, but she came out swinging with confidence, using her big lefty serve and groundstrokes to cruise through the first set. After losing her way somewhat in the second set, she overpowered Halep again in the third.
She broke Halep at love to finish the job, with the Romanian sending one last backhand long on match point.
“I think I was fighting really well,” Vondrousova said in her on-court interview. “It was a very tough match and I was running a lot, and sometimes I felt like I was dying, but I kept fighting every point.”
Vondrousova’s best wins before today were over a pair of world No. 11s last year: Johanna Konta at Indian Wells, and Julia Goerges on clay in Stuttgart. Now, after beating Halep, she’s through to the quarterfinals of a Premier Mandatory event for the first time in her career.
“It’s an amazing week for me,” the 19-year-old from Sokolov said. “It’s actually my first Top 10 win, and I’m just so happy to be through to the quarterfinals, and I’m so happy with my play, as well.
“I love the crowd and all the support here. I’m just enjoying my time here very much.”
Both players struggled with unforced errors on the day: Halep had 36, Vondrousova had 40. But the No. 61-ranked Czech hit more than three times as many winners as the Romanian, 20 to 6. Over half of the games in the match were breaks: Halep broke five times, Vondrousova eight.
Vondrousova has now beaten three seeds in a row—No. 14 seed Daria Kasatkina in the second round, 6-2 6-1; No. 22 seed Jelena Ostapenko in the third round, 4-6 6-3 6-4—and will face either Elina Svitolina or Ashleigh Barty in the quarterfinals. Kasatkina, a finalist at Indian Wells last year, will drop out of the Top 20 next Monday, meaning that for the first time in 21 years, there will not be a Russian in the Top 20 of the WTA rankings.
Halep, meanwhile, is projected to lose her No. 2 ranking on next Monday’s rankings, dipping down to at least No. 3, and potentially lower depending on tournament results.