A sombre looking Sharapova, speaking at a press conference in Los Angeles Monday, said she'd been taking the drug, meldonium, since 2006 and didn't realize it was declared a banned substance by the World Anti-Doping Agency (WADA) at the start of 2016.
The International Tennis Federation, about an hour after her admission, then said on its website
that the 28-year old would be provisionally banned from March 12 "pending determination of the case." The usual penalty for first-time offenders is two years.
The failed drug test came on January 26 -- after Sharapova lost to Serena Williams in the quarterfinals -- and she was charged with an anti-doping violation on March 2, the governing body additionally said.
"A few days ago I received a letter from the (International Tennis Federation) that I failed a drug test at the Australian Open," the five-time grand slam winner said in the press conference that was streamed live on Sharapova's website. "I did fail the test and take full responsibility for it.
"For the past 10 years I have been given a medicine called mildronate by my doctor, my family doctor, and a few days ago after I received the ITF letter I found out that it also has another name, meldonium, which I did not know.
"It's very important for you to understand for 10 years this medicine was not on WADA's banned list and I had been legally taking the medicine for the past 10 years. But on January 1 the rules had changed and meldonium became a prohibited substance, which I had not known."
Sharapova would later say she began taking the medication, which can be used to treat heart issues, after irregular EKGs and being deficient in magnesium. Her family also has a history of diabetes, she added.
Her revelation came on the same day that Russia's Olympic ice dance gold medalist Ekaterina Bobrova said she failed a doping test for the same drug.
'I didn't click that link'
In a statement on its website
, WADA said meldonium was prohibited because of evidence of its use by athletes "with the intention of enhancing performance." The anti-ischemic drug can aid oxygen intake and recovery.
WADA stated in September that the drug would be added to the prohibited list and Sharapova blamed herself for not taking note.
"I received an email on December 22 from WADA about the changes happening to the banned list and you can see prohibited items, and I didn't click that link.
"I made a huge mistake. I let my fans down and I let the sport down. I have been playing since the age of four a sport that I love so deeply.
"I know that with this I face consequences and I don't want to end my career this way. I really hope that I will be given another chance to play (tennis)."
Steve Simon, CEO of the WTA women's tour, was "saddened" by the development but said it was down to Sharapova to make sure she knew the rules.
"I am very saddened to hear this news about Maria," Simon, who became CEO in October, said in a statement. "Maria is a leader and I have always known her to be a woman of great integrity. Nevertheless, as Maria acknowledged, it is every player's responsibility to know what they put in their body and to know if it is permissible.
"This matter is now in the hands of the Tennis Anti-Doping Program and its standard procedures. The WTA will support the decisions reached through this process."
If she is given a full suspension, Sharapova would, easily, become the highest profile tennis player to be sanctioned.
Marin Cilic received a nine-month ban
, before the Croatian became the U.S. Open champion in 2014, and former top-15 pro Viktor Troicki was suspended
for 18 months for failing to provide a blood sample in 2013. Mariano Puerta was banned twice, the second occasion coming months after he made the 2005 French Open final.
Encouragingly for Sharapova, Cilic and Troicki had their suspensions reduced by the Court of Arbitration for Sport, to four and 12 months, respectively.
Martina Hingis, meanwhile, retired for a second time in 2007 after the five-time singles grand slam champion tested positive for cocaine. The Swiss has since returned to tennis, in doubles.
Nick Bollettieri, the Hall of Fame coach instrumental to Sharapova's early success, hoped she would be shown leniency.
"If it was just boom, boom, boom, the drug was illegal for all these years and she knew it, that's a different story," he told CNN by phone. "But when (the email) happened, nine days before the end of the year ... that eased off my pain and I said to myself, 'She's not denying it, she's not trying to say give me mercy, but let me play again.'
"I'm just praying that her record speaks loud and clear, what she's contributed.
"She's handled everything today the way she's handled everything in life, like a lady."
One can only wonder now how sponsors of Sharapova, who is estimated to be worth
$195 million, will react. Sharapova, a rags-to-riches story who was born in Siberia, also runs her own successful candy company, Sugarpova.
"I tell you what I would do if I was one of her sponsors," said Bollettieri. "I would say, 'In life, almost everybody will make mistakes. This young lady said she made a mistake by not reading the banned list and accepted responsibility.'
"If I was a sponsor, I would take that into consideration. She's not saying spare me. She's not asking that."