WIMBLEDON, England -- Serena Williams announced she would not be able to play in the doubles draw at the All England Club alongside sister Venus in an Instagram post Saturday.
"I'm heartbroken to have to withdraw from doubles," Williams wrote. "Coming back to compete again has been a gift, and the opportunity to play alongside [Venus Williams] once more meant the world to me. I did everything I could to be ready, but unfortunately my knee just isn't ready to compete."
Along with a video of herself walking with a heavily bandaged right knee, she included pictures of four syringes that had collected fluid from her knee and of herself receiving treatment.
Williams, 44, who had made her eagerly anticipated return to competition last month, had received a wild card to play both singles and doubles at the grass-court major. She played her first singles match in nearly four years Tuesday against Maya Joint on Centre Court. Williams lost the marathon match 6-3, 6-7 (6), 6-3.
Williams, who did not speak to the media following the loss, issued a statement about the experience.
"It was really great to be back at Wimbledon," Williams said. "I never expected to be here. The atmosphere was amazing. Walking out was amazing. I definitely relished it and missed it and enjoyed the moment more than anything."
The next morning, her agent Jill Smoller released an additional statement explaining that Serena "tweaked her right knee at the end of the first set" in the match but was "doing everything she can to be ready for her doubles match later this week."
Due to the injury, the tournament had given the sisters an additional day to prepare for their opening-round match against Camila Osorio and Solana Sierra. All other first-round matches in the women's doubles draw had concluded by Friday, and they were scheduled for Saturday.
The Williams sisters are 14-time doubles champions, and have won six titles together at Wimbledon.
Williams was not seen on site practicing throughout the week but had been scheduled for a Saturday afternoon session ahead of the match. She made her announcement just moments before that practice was slated to begin. Williams and Venus will be replaced by Samantha Murray Sharan and Lanlana Tararudee.
In her post, Williams thanked the tournament for its support, as well as the fans. She has not yet announced future plans but indicated she would be playing again soon.
"All I can say is stay tuned to a city near you," she wrote.
Venus, 46, played in Wimbledon's mixed doubles draw. Partnering with Kevin Krawietz, the pair was defeated Friday in their opening-round match 6-4, 6-4 by Lloyd Glasspool and Tereza Mihalikova. It was announced earlier in the week that she had received a wild card for August's Canadian Open.