Kim Clijsters led 6-3, 4-3 when No. 12 Vera Zvonareva retired with a respiratory infection. The unseeded Clijsters, who plans to retire after the U.S. Open, is a four-time Grand Slam seeking her first berth in a Wimbledon final.
"It's a pleasure to be a part of the second week of a Grand Slam, especially at Wimbledon," she said.
Americans Sloane Stephens and Christina McHale were eliminated in the third round. The 19-year-old Sloane Stephens was beaten by Sabine Lisicki 7-6 (5), 1-6, 6-2, and the No. 28-seeded McHale lost to No. 8 Angelique Kerber 6-2, 6-3.
No. 3 Agnieszka Radwanska defeated Britain's Heather Watson under the roof, 6-0, 6-2.