Simona Halep and Agnieszka Radwanska suffered surprise losses at the BNP Paribas Open as Angelique Kerber fought through.
Halep, the 2015 champion, wasted chances in a loss to Kristina Mladenovic at Indian Wells on Monday.
Radwanska, seeded sixth and runner-up in 2014 at the WTA Premier event, was also comfortably beaten, going down to qualifier Peng Shuai.
Kerber, who will reclaim the top ranking next week, battled through, joined in the last 16 by Venus Williams, Madison Keys and Caroline Wozniacki.
Halep suffered a third loss in four meetings against Mladenovic, beaten 6-3 6-3 by the French 28th seed.
Mladenovic broke three times in each set as Halep was punished for her missed chances, converting just three of 22 break points.
Halep won 50 return points compared to Mladenovic’s 29, yet bowed out in one hour, 42 minutes.
A qualifier, Peng continued her run with a 6-4 6-4 win over Radwanska.
There were 10 breaks of serve throughout the third-round match, but Peng came away a deserved victor.
Kerber needed more than two and a half hours to get past Pauline Parmentier 7-5 3-6 7-5. The German was forced into a huge battle by Parmentier, coming from 4-1 down in the final set to progress.
Also advancing to the fourth round were Williams, Keys and Wozniacki. Williams remains on track for her 50th WTA Tour title after beating Lucie Safarova 6-4 6-2.
Keys did it easily against Naomi Osaka 6-1 6-4 and Wozniacki cruised past Katerina Siniakova 6-3 6-1.
Elena Vesnina overcame Timea Babos 6-4 1-6 6-4, while Lauren Davis was too good for Julia Goerges 6-1 6-4 in a clash between two unseeded players.
Meanwhile, eighth-seeded Austrian