Earlier today, Venus and Serena Williams were scheduled to play a doubles match in the third round at Wimbledon. But shortly after the match started, the Williams sisters were forced to withdraw from it and concede defeat because Serena was suffering from a "viral illness" of some sort. She released a statement shortly after the match ended to say how "heartbroken" she was about having to call it quits:

But Serena's behavior both before and during the match was bizarre, to say the least. She struggled to pick up tennis balls during warmups, couldn't throw the ball up in the air and serve it cleanly, and just didn't look like herself. In fact, she looked so out of it that ESPN commentator Chris Evert actually questioned whether or not she was on some sort of medication during the match.

"It will be interesting," she said after the sisters revealed that they were not going to be able to play the match. "Is it a virus? Is it something unintentional or intentional in her system that they may drug test for?"

Watch the video above to see Serena in action. What a weird way for her to end her 2014 Wimbledon run.

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[via Business Insider]