Maria Sharapova speaks to the media announcing a failed drug test after the Australian Open during a press conference today at The LA Hotel Downtown.

Tennis star Maria Sharapova has revealed that she failed a drug test at the Australian Open due to the presence of meldonium, a drug used to treat diabetes and low magnesium.

The five-time grand slam champion, who is also the highest-paid woman in sport, said she had been taking the substance for the last ten years because of health issues.

"I made a huge mistake. I let my fans down and I let the sport down. I take full responsibility for it," Sharapova said at a news conference.