MIAMI: Serena Williams got her quest for a record sixth Miami WTA title off to a brisk start on Thursday with a 6-1, 6-1 victory over Italian Flavia Pennetta.

The world No. 1 and top seed, playing her first tournament since falling to Victoria Azarenka in the final at Doha in February, said she didn’t feel too rusty, although her footwork could improve.

Despite the lopsided scoreline, Williams said Pennetta’s ability to extend the rallies made the match difficult, although the American fended off all seven break points she faced.

She had 18 break chances against Pennetta, and converted five, saying she felt a little frustrated that she wasn’t doing more.

Her elder sister Venus Williams also advanced, holding on for a 7-6 (7/3), 3-6, 6-4 victory over Japanese veteran Kimiko Date-Krum.

Fourth-seeded defending champion Agnieszka Radwanska, fifth-seeded Li Na of China and seventh-seeded Petra Kvitova of Czech Republic all joined Williams in the third-round.

Radwanska parlayed an early break in each set into to a 6-3, 6-2 victory over Taiwan’s Hsieh Su-Wei.

Li, playing her first tournament since suffering an ankle injury in her loss to Azarenka in the Australian Open final, downed Kiki Bertens of the Netherlands 6-3, 6-1.

Former Wimbledon champion Kvitova defeated China’s Peng Shuai 5-7, 6-2, 6-2.

Serena next faces Japan’s Ayumi Morita, a 7-6 (7/2), 2-6, 6-3 winner over Belgian Yanina Wickmayer.

Williams is also vying to maintain her spot atop the rankings. A failure to reach the quarterfinals could open the door for either Azarenka or Maria Sharapova to overtake her.

World No. 1 Novak Djokovic will lead men’s seeds into second-round action in this combined WTA and ATP Masters tournament on Friday, against Czech Lukas Rosol. Third-seeded David Ferrer of Spain will take on Dmitry Tursunov of Russia.

In men’s first-round matches on Thursday, 20-year-old Australian Bernard Tomic beat French qualifier Marc Gicquel 7-5, 7-6 (7/3) to set up a second-round meeting with second-seeded Scot Andy Murray.