Mirjana Lucic-Baroni of Croatia turned in a stellar performance to eliminate fifth-seeded Agnieszka Radwanska of Poland in straight sets at the Miami Open on Saturday.
Lucic-Baroni needed only 65 minutes to dispatch Radwanska, the 2012 champion of this event, with a dominating 6-0, 6-3 victory in her third-round match.
Second-seeded Karolina Pliskova of the Czech Republic got past 27th-seeded Yulia Putintseva of Kazakhstan 7-5, 6-3 and fourth-seeded Dominika Cibulkova of Slovakia defeated Kirsten Flipkens of Belgium 6-2, 6-3.
The 26th-seeded Lucic-Baroni, who also upset Radwanska in the second round of the Australian Open in January, will meet American wild-card Bethanie Mattek-Sands in the fourth round.
Radwanska won only 27 percent of her first-serve points and faced 10 break points, with Lucic-Baroni converting on seven of them.
"She was playing unbelievable tennis today," Radwanska said after the match. "She was very solid from the beginning, very aggressive, hitting everything with unbelievable speed. I couldn't do much.
"The first set went so quickly, and in the second set I had chances, but I didn't come back and unfortunately I missed the chance to stay in the match. She was just too good today."
Sixth-seeded Garbine Muguruza of Spain was forced to come from behind for a second straight day, posting a 4-6, 6-2, 6-2 victory over Zhang Shuai of China.
Muguruza, who saved a match point in her three-set victory over American Christina McHale on Friday, needed just over two hours to reach the fourth round.
The Spaniard capitalized on a pair of service breaks to race out to a 4-0 lead in the second set and also recorded a pair of breaks in the third set.
"That first set was just a few points of difference, honestly," Muguruza said. "And then in the second set, I came stronger. I said, 'Look, if yesterday I could come back, I can today as well.'"
Mattek-Sands dropped the first set before rallying for a 4-6, 6-0, 6-3 victory over Russia's Anastasia Pavlyuchenkova, the 17th seed, in her third-round match.
Other third-round winners were No. 15 seed Barbora Strycova and Lucie Safarova of the Czech Republic, who each posted straight-set victories.