Two-time Wimbledon champion Kvitova finally prevailed 6-4, 3-6, 6-4 in the clash between two heavy hitters, requiring more than two-and-a-half hours. Kvitova, the third seed, will next meet France’s Caroline Garcia.
Garcia had earlier knocked out 15th seed Julia Goerges, of Germany, 6-0, 7-5.
Serena Williams, meanwhile, has withdrawn from the Miami event with a left knee injury, tournament officials said on Saturday. It is the second consecutive WTA event in which the American has been unable to continue, after her retirement from last week’s Indian Wells event with illness.
“I hope to be back next year to play at this one-of-a-kind tournament in front of the incredible fans here,” the 36-year-old Williams said.
Former world No.1 Williams, an eight-time Miami Open winner, showed no signs of injury while winning her opener against Swede Rebecca Peterson 6-3, 1-6, 6-1.