Maria Sharapova hopes she still has a future in tennis despite being provisionally suspended following a failed drugs test.

The five-time Grand Slam winner revealed yesterday that she had tested positive for meldonium following her quarter-final defeat against Serena Williams at the Australian Open in January.

Sharapova, who made the shock announcement in a pre-arranged press conference at a downtown Los Angeles hotel, now faces a fight to save her career, with early reports indicating the 28-year-old could be banned for one year.

"We have decided to suspend our relationship with Maria while the investigation continues. We will continue to monitor the situation." - Nike

Sharapova, dressed head-to-toe in black, said: "I let my fans down, I let the sport down that I have been playing since the age of four and I love so deeply.

"I know with this I face consequences. I don't want to end my career this way and I really hope I will be given another chance to play this game."

Meldonium, which Sharapova said she had legally taken throughout her career, was placed on the banned list by the World Doping Anti-Agency at the beginning of the year following "evidence of its use by athletes with the intention of enhancing performance".

Sharapova claimed she did not realise the substance was illegal, but took "full responsibility" for her actions.

The International Tennis Federation said Sharapova had been informed of the positive test on 2 March and she will be provisionally suspended from 12 March.

"'It is very important for you to understand that for 10 years this medicine was not on WADA's banned list and I had legally been taking the medicine for the past 10 years," Sharapova, who claimed she was prescribed the drug by her doctor in 2006 to deal with health issues such as an irregular heartbeat and a history of diabetes in her family, added.

"But on January 1st the rules had changed and meldonium became a prohibited substance, which I had not known. I failed the test and I take full responsibility for it."

Sharapova did not know the extent of the action she now faces from the ITF but Shamil Tarpishchev, president of the Russian Tennis Federation, claimed she could still play for her country at this summer's Rio Olympics.

"I think that it's nonsense," Tarpishchev told Russian news agency TASS of Sharapova's positive test. "Athletes take what their physiotherapists advise them.

"I believe that Sharapova will still have a chance to play at the Olympics though we will see how things are going to develop."

Russia are currently banned from international athletics by the IAAF following a string of doping offences.

Sharapova won her first grand slam as a 17-year-old at Wimbledon in 2004 and has since landed the 2006 US Open title, the 2008 Australian Open and the French Open twice, in 2012 and 2014. She is the highest-paid female athlete in world sport for the last 11 years, according to Forbes.

Sharapova counts financial cost of failed drug test

Nike has since suspended its contract with Sharapova, with watchmaker Tag Heuer and car manufacturer Porsche following suit.

A statement from sportswear giant Nike read: "We are saddened and surprised by the news about Maria Sharapova.

"We have decided to suspend our relationship with Maria while the investigation continues.

"We will continue to monitor the situation."