World number one and eight-time Miami Open champion Serena Williams won through to the fourth round and she was joined by Agnieszka Radwanska.

Williams overcame Zarina Diyas in straight sets in Miami on Saturday as the American veteran improved to a 13-2 this year.

Polish third seed Radwanska advanced after seeing off Madison Brengle 6-3 6-2, while Simona Halep dispatched Julia Goerges 6-4 6-1.


SERENA ON TRACK FOR NINTH TITLE

Williams had to grind through a tough match on the way to securing a 7-5 6-3 victory.

Neither player could find their rhythm on serve in an error-strewn first set in which Williams served three double faults to Diyas' two.

Diyas even broke Williams twice, but the latter bettered that by breaking the 22-year-old three times on the way to claiming the first set.

It looked to be much more straightforward in the second as Williams powered to a 4-0 lead, finding her touch on serve and bullying Dimas on return with her trademark power, but the youngster fought back admirably to 4-3 before the American saw out the match.


KVITOVA AND IVANOVIC SAY GOODBYE

Kvitova missed out on a spot in the fourth round, upstaged by fellow seed Ekaterina Makarova 6-4 6-4.

Trailing 4-1 to the eighth seed, Makarova - the 30th seed - reeled off five successive games as she rallied to win the opening set before closing out the match after breaking for a 3-2 lead in the second.

Serbian 16th seed Ana Ivanovic was eliminated by fellow seed Timea Bacsinszky, who won 7-5 6-4, while Elina Svitolina prevailed against Caroline Wozniacki 5-7 6-4 7-6 (7-1).


MILESTONE WIN FOR SERENA, GOERGES WASTEFUL

Williams posted her 750th career win at the expense of Diyas.

Goerges had eight break-point opportunities against Halep but only converted one in an hour, 34 minutes on court.

Kvitova only won 12 of 40 first return points as she lost out to Makarova.


MIAMI WEATHER A HOT TOPIC

"Today was really hot. And yes, we both kind of have to get used to [the humidity]," Radwanska said afterwards. "Today was a really tough day, and I knew that since this morning. You just try everything to stay cool, especially during the changeovers."

"[It] was actually really tough to play, especially against Petra and in these conditions," Makarova said.

Radwanska said: "One second after the match point, all I'm thinking is: the ice bath!"


NO EGGS ON MENU AS KERBER TAKES CENTRE STAGE

Australian Open champion Angelique Kerber is in action on Easter Sunday, facing Kiki Bertens in the third round. Two-time Miami Open winner and 13rd seed Victoria Azarenka will take on Magda Linette for a spot in the fourth round.