Miami - Russian fourth seed Maria Sharapova and Germany's fifth-seeded Angelique Kerber each battled through three sets on Monday to reach the quarter-finals at the WTA and ATP Miami Masters.
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.
Four-time Grand Slam champion Sharapova had 10 double faults, half of them in the first set, and 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 the winner of a later match between Serbian 12th seed Ana Ivanovic and Czech eighth seed Petra Kvitova.
Kerber put herself in the path of world number one Serena
Williams, the top-seeded defending champion who was set to face US qualifier Coco Vandeweghe in a later fourth-round affair.
Men's world number one Rafael Nadal was set to meet Uzbekistan's Denis Istomin in a later men's third-round matchup.
Canadian 12th seed Milos Raonic blasted 10 aces in defeating Spaniard Guillermo Garcia-Lopez 6-1, 6-2 in 56 minutes. The Montenegrin-born big server next faces either German Benjamin Becker or Slovenia's Aljaz Bedene in the fourth round.