Serena Williams revealed Thursday she had been playing through a "serious" knee injury at the U.S. Open. Williams made the comment after she was stunned by Karolina Pliskova in the semifinals.
Entering Flushing Meadows, Williams hadn't played since a disappointing early exit from the Olympics because of a wrist injury, but she said a new ailment had cropped up during the opening rounds in New York. The 6-2, 7-6 (5) defeat ended her 186-week reign as the world's top-ranked player and postponed her bid for a 23rd grand slam victory.
MORE: Top images from U.S. Open
"I have been having some serious left knee problems," she told reporters after the match. "I wasn't tired. Fatigue had absolutely nothing to do with it. If I was tired I should definitely get into a new career.
"I wasn't able to move the way I wanted to move," Williams added. "When you're injured you're thinking of other things when you should be just playing and thinking of your shots. My mind was just a little bit everywhere. But it was what it was."
Williams, 34, refused to discuss the No. 1 ranking, which she cedes to German Angelique Kerber.
MORE: Serena's U.S. Open titles
She was also unwilling to blame the scheduling, having had less than 24 hours to recover after a quarterfinal win over Simona Halep on Wednesday.
"I wasn't tired from yesterday's match. I'm a professional player; been playing for over 20 years," Williams said. "If I can't turn around after 24 hours and play again then I shouldn't be on tour. So I definitely wasn't tired from yesterday's match at all.
"It wasn't a five-hour match. I have practiced three hours, so it wasn't that huge of a deal."