Maria Sharapova said Monday that she had been notified by the International Tennis Federation that she tested positive for a banned substance at the Australian Open in January.
She won five Grand Slam singles titles and claimed each of the four majors -- the Australian Open, the French Open, Wimbledon and the U.S. Open -- at least once. Her most recent Grand Slam title came at the French Open in 2014.
Sharapova had right shoulder surgery to repair two rotator cuff tears in 2008 and had more shoulder problems in 2013 that she attributed to bursitis, tendinitis and a bone bruise. Before Monday's announcement, she had played only four events in the last eight months: three WTA tournaments and the 2015 Fed Cup final.
Her last match was a quarterfinal loss to Serena Williams at the Australian Open in January.