Second seed Karolina Pliskova cruised into the third round of the Miami Open, the Czech beating American qualifier Madison Brengle 6-1, 6-3 on Thursday.

While her serve was not at its best, the 25-year-old Pliskova never looked in danger, comfortably dominating while winning 78 percent of return points.

"There were a few tight games but I think I was pretty solid. It went quite easy and I was really happy to spend only an hour out there because its pretty hot and humid and so I am happy to save some power for the later matches," said Pliskova.

"The serve wasn't really great and hasn't been for the last few weeks but I think my game from the baseline was better, it's improving, my backhand is better, I was feeling pretty good just want to improve the serve a bit now," she added.

Pliskova reached the semi-finals of Indian Wells last week and she said she was keen to avoid a repeat of last year when she made the last four in California but fell at the first hurdle in Miami.

"It's a big tournament and I wanted to make it better this year. I will be ready for the next one," said the Czech, whose twin sister Kristyna is also in the Miami field.

Slovakian fourth seed Dominika Cibulkova needed to dig deep to fight past Paraguayan qualifier Veronica Cepede Royg.

The 90-minute encounter was far tougher for Cibulkova than the 6-3 6-2 scoreline suggests and she was relieved with the win.

"I just stayed aggressive," she said. "It was my first match here, so it was pretty hot and it wasn't easy conditions. But I made it through. I'd never played her before, so that's always a new experience. I'm glad I got the job done."

Cibulkova faces another tough test, though, against Belgian Kirsten Flipkens, who fought her way past Croatian 29th seed Ana Konjuh 7-6 (7/4), 6-7 (6/8), 6-2.

Agnieszka Radwanska beat China's Wang Qiang 7-6, 6-1 and Caroline Wozniacki comfortably went through 6-1, 6-2 against Varvara Lepchenko.

Sixth-seeded Spaniard Garbine Muguruza was trounced 6-0 in the first set by American opponent Christina McHale and was down 3-2 on McHale's serve in the second when rain began. Play was eventually cancelled for the day and McHale will look to complete the upset on Friday.