Serena Williams withdrew from the Madrid Open on Thursday, telling tournament organizers that she needed more time to train to be fit for the rest of the European clay-court season.
Williams, a 23-time Grand Slam champion, missed 14 months during her pregnancy and after the birth of her daughter, Olympia, in September. Williams returned to the WTA tour in March at the BNP Paribas Open in Indian Wells, Calif., winning two matches before losing in the third round to her sister Venus Williams. Serena Williams then lost her opening match at her next event, the Miami Open, on March 21.