Tennis-Sharapova says failed drug test at Australian Open

LOS ANGELES, March 7 (Reuters) - Former tennis world number one Maria Sharapova said on Monday that she recently received a letter saying she had failed a drug test at the Australian Open. The 28-year-old Russian, a five-times grand slam champion, has not competed since she lost to Serena Williams in the quarter-finals of the Australian Open in January and has struggled with a series of injuries in recent years. (Reporting by Mark Lamport-Stokes; Editing by Frank Pingue)