MIAMI: Reigning Australian Open champion Angelique Kerber and Czech seventh seed Tomas Berdych both advanced to the third round of the ATP and WTA Miami Open on Friday.

Kerber, the second seed from Germany, downed Czech Barbora Strycova 6-1, 6-1 while Berdych, the Miami runner-up in 2010 when he also reached his lone Grand Slam final at Wimbledon, won by walkover when American Rajeev Ram withdrew due to illness.

Berdych, who like all seeds had a first-round bye, will not take the court until Sunday, when he faces either American Steve Johnson or Germany's Alexander Zverev.

Kerber raced through the first set in 32 minutes, firing 10 winners and aided by 15 unforced errors from Strycova, and broke three times in the second set, the last to love to end matters after only 63 minutes.

"I was trying to be focused, just playing my game," Kerber said. "First matches can be tricky."

Next up for Kerber, whose best Miami showing was a 2014 quarterfinal run, is either Dutchwoman Kiki Bertens or Russian 25th seed Anastasia Pavlyuchenkova

World No.1 Serena Williams launched her bid for a ninth Miami Open crown Thursday by outlasting US compatriot Christina McHale 6-3, 5-7, 6-2 to reach the third round.

The 34-year-old defending champion, who like all seeds received a first-round bye, will next face Zarina Diyas of Kazakhstan, who ousted Australian Daria Gavrilova 7-5, 6-3.

Williams, who watched tournaments at the combined WTA and ATP hardcourt event as a child, seeks her fourth consecutive title.

Two-time Wimbledon winner Petra Kvitova reached the third round with a 6-1, 6-4 victory over 83rd-ranked American Irina Falconi.

Kvitova next faces Russian 30th seed Ekaterina Makarova, who ousted Ukraine's Lesia Tsurenko 3-6, 6-4, 6-3.

"I served pretty well," the Czech eighth seed said. "She played better in the second set and that's what made it tougher. It's always a little bit tricky when it's someone you have never played before."

Kvitova next faces Russian 30th seed Ekaterina Makarova, who ousted Ukraine's Lesia Tsurenko 3-6, 6-4, 6-3.

Uzbek Denis Istomin rallied to beat Croatia's Borna Coric 4-6, 7-5, 7-5 in a first-round match to book a Saturday matchup with British second seed Andy Murray, who won their first two meetings back in 2013.