Serena Williams (knee) forced to withdraw from Wimbledon doubles - ESPN

Serena Williams, the 23-time Grand Slam singles champion, has withdrawn from doubles competition at Wimbledon due to a knee injury, she announced Saturday in a post on social media.

Williams injured her right knee during the first set of her singles match of Tuesday's three-set loss to Maya Joint, but remained hopeful to play in the doubles competition alongside older sister Venus.

«I'm heartbroken to have to withdraw from doubles,» Williams wrote on Instagram. «Coming back to compete again has been a gift, and the opportunity to play alongside @venuswilliams 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.»

A post shared by Serena Williams (@serenawilliams)

Serena Williams' post was accompanied by a video showing her favoring the right leg, which had a large wrap on it.

«Thank you to the fans for your incredible support and for making this comeback so meaningful...All I can say is stay tuned to a city near you...»

Williams' singles return set Wimbledon viewing ratings with an average of 1.8 million viewers on ESPN, helping make it the network's biggest audience for a Day 2 at the grass-court Grand Slam.