MADRID, Spain - Arantxa Parra Santonja's two-fisted groundstrokes hit their mark in a big way on the clay courts of the Caja Mágica on Monday, as the Spaniard took out No.13 seed Andrea Petkovic on Spanish soil, 62 76(5).

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Parra Santonja, who had taken out No.20-ranked Flavia Pennetta in the first round on Sunday, continued her good form in her second round match, winning a routine first set against the No.15-ranked Petkovic then battling back from deficits of 4-2 and 5-3 to claim the second set, completing another Top 20 win.

"I've worked hard mentally," the Spaniard said. "I was trying to be optimistic and thought I could do it. I'm so happy. I hope I can continue like this."

Pennetta and Petkovic were the 28-year-old Parra Santonja's third and fourth Top 20 victories. Her first two both came on clay as well, at Warsaw in 2003 (against Magdalena Maleeva, who was ranked No.14 at the time) and at Amelia Island in 2004 (against Francesca Schiavone, who was No.20 at the time).

Next for Parra Santonja is No.4 seed Victoria Azarenka, who followed up her 60 60 first round win with a 61 61 second round win over Sofia Arvidsson. Azarenka won her only prior meeting with Parra Santonja this year.

In the other two second round matches of the day, No.2 seed Vera Zvonareva rebounded from a disastrous 21-minute first set to beat Elena Vesnina, 06 63 63, while No.8 seed Maria Sharapova held her serve 12 of 13 times (and in the only one she lost she led 40-15) for a 63 36 61 win over Ekaterina Makarova.

"When I lost that second set I told myself it wasn't over. I won the first set and did some things right so I went back to that," Sharapova said. "There weren't many breaks in the match and it was important to be more aggressive. She likes to be the first one to hit the ball; I wanted to take that away from her."

Next up for Sharapova is Dominika Cibulkova. "I'm excited I'm in the third round. Dominika is tough, a great clay court player. I'm looking forward to it."

Sharapova leads Cibulkova in their head-to-head series, 2-1.