MIAMI, FL, USA - The underdogs rose up at the Sony Ericsson Open on Friday afternoon, with No.9 seed Vera Zvonareva among the victims as the seeds on the top half of the draw made their first appearances of the fortnight.

Zvonareva, who struggled throughout her February schedule with a hip injury then came down with an illness at Indian Wells last week, having to pull out before her third round match, looked strong as she won the first four games of her match against Garbiñe Muguruza Blanco. But Muguruza Blanco came alive from there, winning eight straight games to take a 64 20 lead, then never really looked back to score by far the biggest win of her career, 64 63.

"I was nervous at the start but as the match went on I felt more comfortable," the 18-year-old Muguruza Blanco said. "I felt like by the end I was playing much better. I was able to play all my tennis. It is really a great result for me."

Muguruza Blanco is playing in the very first WTA main draw of her career.

Angelique Kerber, who had made the semifinals of seven of her last 11 events and was the No.18 seed here, had a similar result - after racing out to a 5-2 first set lead she couldn't put Zheng Jie away, and the Chinese, a former Top 15 player, took complete control and eventually scored a 76(4) 61 upset.

"She has done so well the last half year and her ranking has been going up so fast, so I knew she was a dangerous player," Zheng said. "It was my first time playing her so at the start I didn't really know how to play against her. But I really wanted to win this match so I knew I had to change something.

"In the first set I was making many mistakes, so in the second set I started putting the ball in the court more, but I was still playing aggressively."

Other seeds going to the sidelines were No.27 seed Lucie Safarova, who lost to Heather Watson, 62 61; No.28 seed Monica Niculescu, who led 4-0 in the third set but succumbed to Aleksandra Wozniak, 46 63 64; No.31 seed Kaia Kanepi, who was ousted by Sílvia Soler-Espinosa, 75 63; and finally No.32 seed Nadia Petrova, who lost to the tenacious Simona Halep, 63 62.

"When you play someone who slices and hits two handed from both sides, it's tough," Wozniak commented. "It was a tough match. We had a lot of long rallies and it was really hot out there, but I pulled it together and got the win."

No.15 seed Ana Ivanovic, No.16 seed Dominika Cibulkova and No.24 seed Flavia Pennetta were among the seeds moving through on a hot Friday.

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