Shahar Pe'er qualified for the quarterfinals at a WTA Tour event for the fifth time this year Wednesday at the Thailand Open in Bangkok, but saw her chances for a third straight doubles semifinal fall apart Thursday when her partner pulled out injured. Pe'er, who is ranked 48th in the world and seeded eighth at the Tier III tourney, overcame a bad serve day to oust American Shenay Perry (97) in the second round, 6-4, 5-7, 7-6(2). In Friday's quarterfinals, the Israeli teenager will take on Italian Antonella Serra Zanetti (74) seeking her first-ever semifinal appearance. Pe'er and Serra Zanetti have split their previous two meetings. Pe'er came out on top in the more recent encounter in straight sets earlier this year in Miami. Fifth seed Sania Mirza (31) of India withdrew during her second round singles match on Thursday with a lower back strain. As a result, Pe'er and Mirza, doubles semifinalists last week in Tokyo, were forced to pull out of their doubles quarterfinal against second seeds Shinobu Asagoe of Japan and Argentina's Gisela Dulko. Andy Ram and Yoni Erlich will look to book a spot in the semifinals at the BA-CA Tennis Trophy in Vienna Friday when they take on Frenchman Sebastien Grosjean and Czech Radek Stepanek. The Israelis, ranked ninth in the ATP doubles race, could take a huge step towards their goal of reaching the season-ending Masters Cup in Shanghai with a strong run in Vienna. On the men's challenger circuit, Noam Okun (172) was injured and Harel Levy (249) and Dudi Sela (175) both lost to end their participation at the Swanston Challenger in Sacramento, California. Levy fell 2-6, 6-3, 6-2 to Rajeev Ram (212) in the second round, while Sela, seeded eighth, lost his opening match against Zack Fleishman (281) 7-5, 4-6, 6-1. Okun's second round encounter against Michael Russell (570) ended when the Israeli No. 1 pulled out with a neck injury while leading 6-2, 2-5. His withdrawal forced Levy and Okun to pull out of the doubles event as well.