Top seed Vera Zvonareva dispatched fellow Russian Vera Dushevina 6-3, 6-0 at the Mercury Insurance Open.
Number two seed Germany’s Andrea Petkovic advanced the quarterfinals when her opponent France’s Virginie Razzano retired with a right shoulder injury.
Poland’s Agnieska Radwanska demolished US teen Christina McHale 6-1, 6-0 while fifth seed Ana Ivanovic cruised past Italy’s Alberta Brianti 6-1, 6-2.
Daniela Hantuchova of the Slovak Republic stopped China’s Zheng Jie 6-2, 4-6, 6-4.
Shuai Peng rallied from a 1-3 third set deficit  to defeat No. 16 seed Sara Errani of Italy 4-6, 6-2, 7-6 (7). Hard serving Sabine Lisicki held back Coco Vandeweghe 6-4, 6-3.
American Sloane Stephens advanced to her first WTA tournament quarterfinal when her Austrian opponent Tamira Paszek was forced to retire with a left abdominal injury trailing 5-3.
RESULTS – AUGUST 04, 2011
Women’s
Singles – Third Round
[1] V Zvonareva (RUS) d V Dushevina (RUS) 63 60
[2] A Petkovic (GER) d V Razzano (FRA) 62 30 Retired
[3] A Radwanska (POL) d C Mchale (USA) 61 60
[4] S Peng (CHN) d [15] S Errani (ITA) 46 62 76(7)
[5] A Ivanovic (SRB) d A Brianti (ITA) 61 62
[8] D Hantuchova (SVK) d J Zheng (CHN) 62 46 64
[12] S Lisicki (GER) d C Vandeweghe (USA) 64 63
[WC] S Stephens (USA) d T Paszek (AUT) 53 Retired
Women’s
Doubles – Quarterfinals
[1] K Peschke (CZE) / K Srebotnik (SLO) d K Date-Krumm (JPN) / S Zhang (CHN) 64 62
S Errani (ITA) / R Vinci (ITA) d A Rodionova (AUS) / O Savchuk (UKR) 75 64
V Dushevina (RUS) / L Hradecka (CZE) d E Bovina (RUS) / J Zheng (CHN) 63 63
ORDER OF PLAY – FRIDAY, AUGUST 05, 2011
STADIUM COURT start 11:30 am
[8] D Hantuchova (SVK) vs [3] A Radwanska (POL)
Not Before 2:00 PM
[WC] S Stephens (USA) vs [2] A Petkovic (GER)
Not Before 4:15 PM
[1] V Zvonareva (RUS) vs [12] S Lisicki (GER)
Not Before 8:00 PM
[4] S Peng (CHN) vs [5] A Ivanovic (SRB)