BANGKOK — Top-seeded Vera Zvonareva overpowered Yaroslava Shedova of Kazakhstan 6-4, 6-4 on Thursday to reach the Pattaya Open quarterfinals.

Thai hope Tamarine Tanasugarn and Israel's Shahar Peer also advanced to the last eight.

The fifth-ranked Zvonareva struggled at times against Shedova but managed crucial breaks in the 10th game of the first set and again in the opening game of the second to win in 1 hour, 40 minutes.

"It was difficult coming off a Grand Slam and play a new tournament which has different conditions, especially here which is hot and has two courts next to each other. It's difficult to concentrate because of the noises," the Russian said.

"My level of game is not there yet but I fought hard for every point and played clean service games and didn't give her a chance to break."

Zvonareva will play Peng Shuai of China in the quarterfinals, with the Russian boasting a 4-0 record in their head-to-head meetings.

"She is an up-and-coming player," Zvonareva said. "She can be very dangerous if she keeps working hard like she is doing now. She has a few good wins. Every time we play, they've been tough three sets."

The seventh-seeded Peer, the 2006 Pattaya champion, reached the quarters with a 6-4, 6-1 win over Yuliya Beygelzimer of Ukraine in just 73 minutes. Peer will next face Russia's Vera Dushevina.

Tanasugarn, seeded sixth, beat Portugal's Neuza Silva 6-3, 6-2.