Williams, Sharapova advance in Sony Open

Key Biscayne, FL ( - Defending champion Serena Williams and Maria Sharapova highlighted Thursday's second-round winners at the $5.4 million Sony Open.

The top-seeded Williams, a six-time Miami champ who topped the five-time runner-up Sharapova in last year's final, was taken to an extended first-set tiebreaker by Kazakhstan's Yaroslava Shvedova before ultimately disposing of the world's 59th-ranked player by a 7-6 (9-7), 6-2 score on the hardcourts of Crandon Park.

Sharapova, seeded fourth, had an easier time topping Japan's Kurumi Nara with a 6-3, 6-4 verdict.

Fifth-seeded German Angelique Kerber snuck into the third round with a 6-3, 1-6, 7-6 (7-5) victory over Chinese Peng Shuai, while eighth-seeded Czech slugger Petra Kvitova handled Argentine Paula Ormaechea, 6-3, 6-4. No. 9 seed Sara Errani also prevailed in straight sets, with the Italian star downing Austrian qualifier Patricia Mayr-Achleitner 6-1, 6-4.

Elsewhere, 12th-seeded former world No. 1 Ana Ivanovic whipped American Lauren Davis 6-1, 6-1; 14th-seeded and 2013 Wimbledon finalist Sabine Lisicki rallied to top wild card Nadia Petrova 3-6, 6-4, 6-4 and and last week's surprise Indian Wells champ Flavia Pennetta, seeded 20th this week, stayed hot by erasing Belarusian qualifier Olga Govortsova 6-3, 6-3.

American qualifier Coco Vandeweghe scored the day's biggest upset, toppling 21st-seeded Anastasia Pavlyuchenkova 7-6 (9-7), 7-5.

Also, 16th-seeded Sam Stosur stopped Dutch qualifier Kiki Bertens 6-3, 6-2; No. 19 seed Kirsten Flipkens bested French qualifier Virginie Razzano 6-1, 3-6, 6-3; 26th-seeded Czech Lucie Safarova bested American Vania King 6-3, 7-6 (7-2); Frenchwoman Caroline Garcia upended 27th-seeded Czech Klara Zakopalova 7-6 (7-3), 7-6 (7-3); and Croatian qualifier Donna Vekic doused 28th-seeded 2006 Miami champion Svetlana Kuznetsova 7-6 (7-5), 7-5.

Garcia's victory earns her a third-round match with Williams, also a runner up at this even in 1999 and 2009.

In other action involving seeds, No. 23 Russian Ekaterina Makarova drilled Swedish wild card Rebecca Peterson 6-1, 6-1 and Bulgarian Tsvetana Pironkova ousted No. 25 Romanian Sorana Cirstea 6-3, 6-3.

The winner of this lucrative event will collect $787,000.