Kerber was stunned by No. 16 seed Elina Svitolina 6-3, 7-5, who moves on to a quarterfinal match against Daria Gavrilova, a 6-4, 6-3 winner over Caroline Garcia. Playing in the same half of the bracket, No. 3 seed Agnieszka Radwanska dominated Caroline Wozniacki 6-3, 6-2 in their third meeting in as many weeks. Wozniacki beat Radwanska en route to winning the Toray Pan Pacific Open two weeks ago, before Radwanska evened the score at the Wuhan Open last week.
"I don't think it happened to me ever to play someone three weeks in a row," Radwanska said. "Good we're playing in different tournaments next week so we can't play against each other again!
"We've known each other for 17 years. Practicing together as well almost every tournament, playing some matches against each other. I think we know about each other everything."
Pliskova entered as the No. 5 seed, but was dispatched by No. 11 seed Johanna Konta 6-1, 3-6, 7-6 (2) in a match that lasted two hours and seven minutes. Konta will next face China's Shuai Zhang, the unseeded fan favorite who stunned Halep 6-0, 6-3 in under one hour.
Zhang, ranked 36th in the world, beat Halep in the opening round of the Australian Open earlier this year and is the first Chinese woman to reach the quarterfinals of the China Open since Li Na in 2013.
"I feel I played much more better today than in Australia Open because I have more confidence," Zhang said after the match, via WTATennis.com. "Especially because we are in the China Open, my favorite tournament, so I'm really happy."
The other quarterfinal in the bottom half of the draw will feature No. 8 seeded American Madison Keys against No. 14 seed Petra Kvitova in a match between players trying to moved up into the top eight seeds for the season-ending WTA Tour Finals in Singapore beginning Oct. 23. Konta is also trying to make a late surge to qualify, and must at least reach the finals in Beijing to stay in the mix for Singapore.
Svitolina, who beat Serena Williams at the Rio Olympics in August, continued her strong late-season form with the upset of Kerber, who has not reached the quarterfinals in two tournaments since taking over the No. 1 world ranking.
"I was just trying to be really focused on every ball, and of course try to win," Svitolina said in her on-court interview.