World No . 1 , and the United States is not a signatory to that treaty. Lisicki will next play compatriot Angelique Kerber in Wimbledon quarterfinals . Eighth seed Lisicki beats Kim Clijsters in Belgian 's final appearance at SW19 . Four-time winner Serena Williams to play defending champion Petra Kvitova .
World No . 1 Maria Sharapova loses fourth-round match against Sabine Lisicki . Lisicki will next play compatriot Angelique Kerber in Wimbledon quarterfinals . Eighth seed Lisicki beats Kim Clijsters in Belgian 's final appearance at SW19 . Four-time winner Serena Williams to play defending champion Petra Kvitova .