Maria Sharapova shocked the sporting world by announcing at a press conference in Los Angeles on Monday she had failed a drugs test at the Australian Open.
The five-time Grand Slam champion has not yet been told what sanction she faces but has accepted a provisional ban.
Press Association Sport looks at other high-profile doping cases in tennis.
The Croatian was given a nine-month ban in 2013 after the International Tennis Federation (ITF) said traces of banned stimulant nikethamide were found in a sample he gave at a tournament in Munich. Cilic claimed the failed test was a result of taking over-the-counter glucose tablets, but argued only a by-product of the banned substance had been found. He took his case to the Court of Arbitration for Sport (CAS) and the ban was reduced to four months. Cilic won his first grand slam title at the US Open the following year.
Another recent and controversial case. Troicki refused to take a blood test at a tournament in Monte Carlo in 2013, claiming he was feeling unwell and had a phobia of needles. He was banned for 18 months, reduced to 12 on an appeal to CAS. Troicki vociferously maintained his innocence, claiming he had been told by the doping control officer he could take the test the following day. Novak Djokovic spoke out in impassioned defence of his friend, calling it an injustice and claiming he had lost faith in the system.
Gasquet tested positive for cocaine in 2009 and was banned for 12 months by the ITF. He also took his case to CAS and successfully argued he had ingested the substance inadvertently after kissing a woman in a nightclub. He was cleared of any wrongdoing.
Agassi made the shocking revelation in his post-retirement autobiography that he failed a test in 1997 after taking crystal meth and then lied to tennis authorities to escape punishment. He told the ATP in a letter he had taken the drug accidentally. The governing body believed him and the failed test remained a secret for the rest of Agassi’s playing career.
The former British No.1 was among a number of players to test positive for the steroid nandrolone in 2003. He was cleared of wrongdoing after a tribunal ruled he, along with the other players, had taken the drug inadvertently in contaminated pills handed out by ATP trainers.
Having initially retired in 2003 at the age of 22, Hingis returned to tennis two years later only for her comeback to be abruptly ended in 2007 by a positive test for a metabolite of cocaine at Wimbledon. She was suspended from tennis for two years but made another comeback in 2013 and is now ranked No.1 in the world in doubles.
Probably tennis’ most notorious doping offender. In March 2010, the American pleaded guilty to importing human growth hormone into Australia and was suspended for two years. The ban was later reduced to one year after the ITF said he had fully cooperated with their investigations. Odesnik became something of a pariah and was banned for 15 years in March last year after a second offence, this time testing positive for a number of banned substances, including steroids.
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