Serena Williams withdrew from the women’s doubles event at Wimbledon due to a right knee injury, ending her planned reunion with sister Venus Williams at the tournament.The 44-year-old suffered the injury on his return to singles earlier this week, where he lost in three sets.Announcing her withdrawal in an Instagram post, Serena wrote: “I’m sad to have to withdraw from doubles. Coming back to compete again is a gift, and the opportunity to play with Venus Williams once again means the world to me. I’m doing everything I can but unfortunately my knee isn’t ready to compete yet.”Along with the post, Serena shared photos of four syringes, saying they showed “the fluid they drained from my knee after my singles match.” He also posted a video of himself walking with a heavy bandage on his right leg, while one of his daughters appeared to carry a cane for him.Despite the setback, Serena suggested she could return to competition soon, with the US Open just around the corner.“All I can say,” Serena added, “is go to a town near you.”The Williams brothers are scheduled to face Camila Osorio and Solana Sierra in the first round. Their match was the only women’s doubles first-round contest that was not played earlier in the week, after it was delayed to give Serena more time to recover.Serena returned to singles action on Tuesday but was defeated by 20-year-old Maya Joint of Australia, 6-3, 6-7 (6), 6-3.Venus also participated in the mixed doubles event on Friday with Kevin Krawietz. The pair lost in straight sets to Tereza Mihalikova and Lloyd Glasspool.The Williams sisters won six Wimbledon women’s doubles titles together.