Four-time champion Serena Williams overcame windy conditions and a gritty 65th-ranked opponent on Monday to pull out another three-set victory and reach the quarterfinals of Wimbledon. The sixth-seeded American won the last three games of the final set to beat Kazakhstani wild card Yaroslava Shvedova 6-1, 2-6, 7-5 in cool and gusty conditions on Court 2. Williams hopped in joy with both feet in the air after hitting a big forehand that forced an error by Shvedova on the first match point, ending a hard-hitting contest that lasted nearly two hours. ‘’I didn’t want to lose today and I thought, ‘Just stay relaxed,’’’ Williams said. ‘’I knew the whole match I could play better.’’ Williams will next face defending champion Petra Kvitova, who rallied from a set and a break down to beat former French Open winner Francesca Schiavone 4-6, 7-5, 6-1 in an error-filled match on Court 3. It was the second straight tough three-set victory for Williams, who won 9-7 in the third to beat Zheng Jie in the previous round. ‘’I feel fine,’’ she said. ‘’I’m not tired. I’m not anything. I feel good. I feel like, bottom line, I can play so much better than what I have been playing. … You know me. I’m never satisfied.’’ The match ended in a slight drizzle, with play suspended on some of the other courts. Shvedova removed her glasses in the final two games to keep the lenses from getting wet. ‘’I think we both wanted to keep playing because it was so deep into the match,’’ Williams said. ‘’I didn’t want to stop.’’ Williams finished with 35 winners, including 12 aces, and 13 errors. Shvedova had 24 winners and 20 errors.