Tournament organizers say Wimbledon champion Petra Kvitova, French Open winner Li Na and Vera Zvonareva have pulled out of the Dubai Tennis Championships because of illness and injury. Organizers did not give details. Last week, Zvonareva retired from the Qatar Open while trailing Monica Niculescu of Romania 7-5, 3-2 because of pain in her left hip, while Kvitova pulled out of that tournament with an unspecified injury. Australian Open champion Victoria Azarenka is the top-seeded player at Dubai tournament, which starts Monday. The field also includes defending champion Caroline Wozniacki and U.S. Open winner Sam Stosur.