Maria Sharapova failed drug test at Australian Open

US sportswear giant Nike wasted no time in distancing itself from one of its biggest brand ambasadors.

Maria Sharapova lost to Serena Williamsin the quarter-finals at Melbourne.

US sportswear maker Nike wasted no time in distancing itself from one of its biggest brand ambasadors, Maria Sharapova.

Just hours after the tennis star revealed she had failed a drugs test at the Australian Open in January, Nike announced it was halting its relationship with her.

“We are saddened and surprised by the news about Maria Sharapova,” Nike said in a statement. “We have decided to suspend our relationship with Maria while the investigation continues.”

According to Forbes, she earned $US29.5 million ($A39.47m) in 2015, mostly from endorsements.

The 28-year-old Russian made the announcement in a news conference earlier today at Los Angeles. Unaware of what punishment she faced, Sharapova said she did not want her career to end this way.

“A few days ago I received a letter from the ITF that I had failed a drug test at the Australian Open. I failed the test and I take full responsibility for it,” she said.

“For the past ten years I have been taking a medicine called Mildronate by my doctor, my family doctor, and a few days ago after I received the letter I found out that it also has another name of Meldonium, which I did not know. It’s very important for you to understand that for ten years this medicine was not on WADA’s banned list and I had been legally taking the medicine for the past ten years. But on January first the rules changed and Meldonium became a prohibited substance, which I had not know.

Maria Sharapova lost to Serena Williamsin the quarter-finals at Melbourne.

Sharapova received an email from the World Anti-Doping Agency on December 22 that highlighted changes to tennis’s banned substances for 2016. She said that the email included a link to the list, but that she failed to look at it.

Last year, WADA added Meldonium to the prohibited list because of evidence of its use by athletes with the intention of enhancing performance. A penalty is yet to be announced for the world’s highest-paid female athlete for 11 consecutive years. Sharapova said she would co-operate with all ITF inquiries.

Sharapova said she started taking the drug because she was “getting sick very often, and I had a magnesium deficiency. I also had irregular EKG results, and I have a family history of diabetes.”

There was speculation that Sharapova had called the press conference to announce her retirement.

“If I was retiring, it wouldn’t be in a downtown L.A. hotel with this ugly carpet,” she said. “I take great responsibility in my job every day. I made a huge mistake and I let my fans down and let the sport down that I’ve been playing since age four and that I love so deeply. I don’t want to end my career this way, and I hope I’m given another chance to play this game.”

Sharapova was beaten by World No. 1 Serena Williams in the quarter-finals of the Australian Open.

Sharapova’s penalties could range from a multiyear ban to a minimal sanction with no suspension if officials believe she made an honest mistake. WADA President Craig Reedie told The Associated Press that any athlete found guilty of using meldonium would normally face a one-year suspension.

The ITF’s anti-doping program announced in a statement that Sharapova will be provisionally suspended starting this weekend while her case is examined.

WADA spokesman Ben Nichols said the organization “will refrain from commenting further until a decision has been issued by the ITF. Following that, WADA will review the reasons for the decision and subsequently decide whether or not to use its independent right of appeal to the Court of Arbitration for Sport.”

With agencies