Miami - Third seed Simona Halep defeated Italy's Camila Giorgi 6-4, 7-5 on Sunday to advance into the Miami Masters fourth round.
The winner a week ago of the Indian Wells title oveercame five double-faults in a victory requiring nearly 90 minutes.
The Romanian is bidding for a fourth WTA title this season after triumphing at Shenzhen, Dubai and Indian Wells.
Results on Sunday from the sixth day of the ATP and WTA Miami Open (x denotes seeded player):
Women
3rd round
Simona Halep (ROM x3) bt Camila Giorgi (ITA x30) 6-4, 7-5
Svetlana Kuznetsova (RUS x24) bt Angelique Kerber (GER x13) 6-3, 3-6, 6-3
Serena Williams (USA x1) bt Catherine Bellis (USA) 6-1, 6-1
Sara Errani (ITA x11) bt Garbine Muguruza (ESP x21) 4-6, 6-4, 6-1
Flavia Pennetta (ITA x15) bt Victoria Azarenka (BLR) 7-6 (7/5), 7-6 (8/6)
Sloane Stephens (USA) bt Johanna Larsson (SWE) 6-4, 6-4
Belinda Bencic (SUI) bt Tatjana Malek (GER) 6-4, 7-5
Sabine Lisicki (GER x27) bt Ana Ivanovic (SRB) 7-6 (7/4), 7-5
Men
3rd round
Kevin Anderson (RSA x15) bt Leonardo Mayer (ARG x24) 6-4, 6-4
Andy Murray (GBR x3) bt Santiago Giraldo (COL x27) 6-3, 6-4
Dominic Thiem (AUT) bt Jack Sock (USA) 6-4, 6-3
Adrian Mannarino (FRA x28) bt Stan Wawrinka (SUI x7) 7-6 (7/4), 7-6 (7/5)
Gael Monfils (FRA x17) bt Jo-Wilfried Tsonga (FRA x11) 6-4, 7-6 (7/4)
Fernando Verdasco (ESP x29) bt Rafael Nadal (ESP x2) 6-4, 2-6, 6-3
Tomas Berdych (CZE x8) bt Bernard Tomic (AUS) 6-7 (4/7), 7-6 (7/3), 6-1
Juan Monaco (ARG) bt Guillermo Garcia-Lopez (ESP x23) 7-5, 6-4