Queen’s Club, LONDON — Victoria Mboko was forced to withdraw from her singles match against Karolína Plíšková at Queen’s on Wednesday afternoon with a left knee injury. That put her out of her doubles quarterfinal with Serena Williams, scheduled for Thursday, and the rising teenage star has now withdrawn from Wimbledon, the third Grand Slam of the year.Williams and Mboko beat Erin Routliffe and Nicole Melichar-Martinez on Tuesday in what was the American’s first match for almost four years, and they were in line to face Laura Siegemund of Germany and Canada’s Leylah Fernandez.But Mboko, the 19-year-old singles world No. 9 from Canada, suffered a nasty fall against Plíšková of the Czech Republic.Mboko was down a set, but up 4-3 in the second, when she took a nasty fall on the baseline. Her right leg slid out as she moved laterally, with her left leg buckling as a result, and Mboko went down clutching at her left knee. After about a minute on the floor, Mboko was able to get up but was fighting back tears as she spoke to the trainer.The Canadian was then able to walk to her chair, where she covered her face with a towel as she received treatment. Mboko, who described the sensation of having “no stability” on her left knee, promptly retired from the match, and left the court unaided. A left knee injury was later given as the reason for her withdrawal in a tournament statement.