Simona Halep and Victoria Azarenka advanced to the Miami Open third round as Serena Williams' match was cancelled due to rain.

Romanian Halep overcame returning Czech wildcard Nicole Vaidisova 6-4 2-6 6-1 despite serving poorly throughout the deciding set in the second-round clash.

The third seed put in just 38 per cent of first serves in the third set, but Vaidisova managed to win just five return points.

That helped Halep advance, setting up a meeting with Italian Camila Giorgi.

The 30th-seeeded Giorgi was too good for Belgian qualifier Alison Van Uytvanck 6-3 6-2.

Azarenka, unseeded as she continues her return from injury, thrashed Serbian Jelena Jankovic 6-1 6-1.

The Belarusian is a two-time champion in Miami and battled past Jankovic, who wasted all 13 break points she had.

Azarenka will meet Flavia Pennetta after the Italian 15th seed edged Bulgarian Tsvetana Pironkova 6-7 (1-7) 6-3 6-3.

Williams was due to face Monica Niculescu, but rain in Miami saw that clash cancelled.

One American who did advance was 15-year-old Catherine Bellis, who crushed Kazakh Zarina Diyas 6-2 6-1.

Ana Ivanovic needed two hours, 35 minutes to book her place in the next round.

The Serbian's opponent Irina Falconi served 12 double faults as Ivanovic clinched a 7-5 6-7 (4-7) 6-3 win over the qualifier.

Lucie Safarova suffered a surprise loss, the Czech 10th seed beaten by Johanna Larsson 7-6 (7-5) 6-2.

The clash between two hard-hitting Americans went the way of Sloane Stephens, who beat Madison Keys 6-4 6-2.

In an all-German affair, Sabine Lisicki beat Julia Goerges 7-6 (7-1) 6-7 (5-7) 6-4, while Garbine Muguruza was untroubled by Sesil Karatantcheva in a 6-1 6-3 win.

Russian Svetlana Kuznetsova powered past Alison Riske 6-2 6-2 and Belinda Bencic overcame Australian 32nd seed Casey Dellacqua 6-2 4-6 6-2.

A pair of matches will finish on Saturday.

Sara Errani leads Anastasia Pavlyuchenkova 6-1 4-1, while Angelique Kerber took the first set against Heather Watson 7-5.