Miami - World number one Serena Williams breezed into the quarter-finals of the WTA and ATP Miami Masters on Monday while Russian fourth seed Maria Sharapova battled through three sets to advance.
Top-seeded defending champion Williams routed US qualifier Coco Vandeweghe 6-3, 6-1 in 78 minutes to book a last-eight matchup 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 quarter-final 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.' But it was really good for me to win this match."
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.
"It's not like I didn't have my opportunities in those finals. I just didn't take them. That's why you come back and hope for another chance."
Sharapova made 10 double faults, half of them in the first set, and served no aces but improved as the match progressed and in the final set won five of 12 points off the Belgian's first serve and seven of nine off her second serves.
Next up for Sharapova will be Czech eighth seed Petra Kvitova who beat Serbian 12th seed Ana Ivanovic 3-6, 6-0, 6-0.
On the men's side of the draw, world number one Rafael Nadal and hard-serving Canadian Milos Raonic barely broke a sweat in recording straight set victories Monday.
Nadal made short work of Uzbekistan's Denis Istomin, winning their third round contest in a rout, 6-1, 6-0, while 12th seed Raonic blasted 10 aces in defeating Spaniard Guillermo Garcia-Lopez 6-1, 6-2 in 56 minutes.
A three-time Miami runner-up, Nadal needed just 59 minutes to oust Istomin at the Crandon Park courts.
Next up for the reigning US and French Open champion Nadal will be 14th-seeded Fabio Fognini of Italy, who battled back to beat Spaniard Roberto Bautista Agut 4-6, 6-3, 6-3.
Raonic, who dropped only five points on his serve in the match, reached the last 16 at Miami for the first time after being forced to withdraw from third-round matches with injuries the past two years.
"I just generally improved, especially on second serve returns (and) taking advantage more of those opportunities," Raonic said.
He next faces German Benjamin Becker, who beat Slovenia's Aljaz Bedene 6-3, 7-5.
"It's going to be a tough match but it's up to me," Raonic said. "I've got to play well. If I do, I can always give myself an opportunity to do well."
Meanwhile, Stanislas Wawrinka sailed into the fourth round with a 7-5, 6-4 triumph over France's Edouard Roger-Vasselin. The 28-year-old Swiss Wawrinka will next face Alexandr Dolgopolov after the 22nd-seeded Ukrainian rallied for a 3-6, 6-0, 7-6 (7/5) victory over Serbian lucky loser Dusan Lajovic.
Results on Monday from the seventh day of the WTA and ATP Miami Masters (x denotes seeded player):
Milos Raonic (CAN x12) bt Guillermo Garcia-Lopez (ESP) 6-1, 6-2
Alexandr Dolgopolov (UKR x22) bt Dusan Lajovic (SRB) 3-6, 6-0, 7-6 (7/5)
Benjamin Becker (GER) bt Aljaz Bedene (SLO) 6-3, 7-5
Rafael Nadal (ESP x1) bt Denis Istomin (UZB) 6-1, 6-0
Fabio Fognini (ITA x14) bt Roberto Bautista (ESP) 4-6, 6-3, 6-3
Stanislas Wawrinka (SUI x3) bt Edouard Roger-Vasselin (FRA) 7-5, 6-4
John Isner (USA x10) bt Nicolas Almagro (ESP x18) 7-5, 6-3
Tomas Berdych (CZE x7) bt Joao Sousa (POR) 6-2, 6-4
Maria Sharapova (RUS x4) bt Kirsten Flipkens (BEL x19) 3-6, 6-4, 6-1
Angelique Kerber (GER x5) bt Ekaterina Makarova (RUS x23) 6-4, 1-6, 6-3
Serena Williams (USA x1) bt Coco Vandeweghe (USA) 6-3, 6-1
Petra Kvitova (CZE x8) bt Ana Ivanovic (SRB x12) 3-6, 6-0, 6-0
Agnieszka Radwanska (POL x3) bt Elina Svitolina (UKR) 7-6 (7/5), 5-7, 6-2
Li Na (CHN x2) bt Carla Suarez (ESP x15) 6-0, 6-2
Caroline Wozniacki (DEN x11) bt Varvara Lepchenko (USA) 6-0, 6-1
Dominika Cibulkova (SVK x10) bt Venus Williams (USA x29) 6-1, 7-5, 6-3