MIAMI - World number one Serena Williams has breezed into the quarterfinals of the WTA and ATP Miami Masters, while Russian fourth seed Maria Sharapova has battled through three sets to advance.
Top-seeded defending champion Williams routed US qualifier Coco Vandeweghe 6-3, 6-1 in 78 minutes on Monday to book a last-eight meeting with German fifth seed Angelique Kerber.
Sharapova rallied to defeat Belgium's Kirsten Flipkens 3-6, 6-4, 6-1 after two hours and four minutes, while Kerber took six minutes longer to eliminate Russia's Ekaterina Makarova 6-4, 1-6, 6-3.
Williams smashed 17 winners to only 11 unforced errors and denied her compatriot on all six of her break-point chances to book her 13th quarterfinal in 14 Miami appearances.
"It was a much tougher match than the scoreline showed," Williams said.
"Coco has such an amazing serve, so every time I was returning I was like, 'Hopefully I can touch the ball'."
Williams owns a 3-1 career edge over Kerber, whose lone win came two years ago on Cincinnati hardcourts.
"Angelique is really good and moves really, really well," Williams said.
"I feel better than I did in my first few matches, though, so I hope I can keep going forward."
Four-time Grand Slam champion Sharapova, a five-time Miami runner-up, is still seeking her first title at the hardcourt event.
"Of course it would be meaningful for me to win this tournament after being so close. Definitely," Sharapova said.