Five-time Grand Slam champion Maria Sharapova announced at a news conference Monday that she failed a drug test at the Australian Open.

The current world No. 7 said she was notified by the International Tennis Federation several days ago. The Tennis Anti-Doping Program confirmed to The New York Times that she will be "provisionally suspended" starting on March 12, "pending the determination of the case."

The 28-year-old, who most recently lost to Serena Williams in the Australian Open quarterfinals in January, said she tested positive for meldonium, a substance she has been taking since 2006.

"I had several health issues going on at the time," Sharapova said, according to Reuters. "I was getting sick very often ... and I had a deficiency in magnesium and a family history of diabetes, and there were signs of diabetes. That is one of the medications, along with others, that I received."

According to ITF documents, meldonium was moved from the "monitoring program" and added to the "prohibited list" beginning in 2016.

"I failed the test and take full responsibility for that," Sharapova said, according to the BBC. "I had been taking this medicine for the past 10 years, but on Jan. 1 this became a prohibited substance which I did not know."

She added: "I received an email on Dec. 22, 2015 from WADA [World Anti-Doping Agency] about the changes happening to the banned list and you can see prohibited items, and I didn't click on that link."

When Sharapova, who withdrew from this week's BNP Paribas Open at Indian Wells owing to injury, announced her intent to hold a news conference to make an announcement, there was rampant speculation that she would be retiring. She shot down those rumors, saying, "I know I face consequences and I didn't want to end my career this way. I hope I will be given the chance to play this game again."

Sharapova also offered a joke, saying if she was retiring she wouldn't announce it at "a hotel in downtown Los Angeles with some fairly ugly carpet."

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