New Delhi: Russian-born tennis star Maria Sharapova admitted to failing a dope test during this year’s Australian Open. Sharapova said she received a letter from the International Tennis Federation (ITF) some days ago informing her that she had failed the test for meldonium. The tennis star’s family doctor had been giving her mildronate, which is also called meldonium, for 10 years as she frequently became sick, had irregular electrocardiogram (ECG) results, a magnesium deficiency and had a family history of diabetes. The 28-year-old may face a four-year ban. As the verdict is awaited, here is a list of 5 international tennis players involved in doping scandals.

1.Marin Cilic: The Croatian was given a nine-month ban in 2013 after the International Tennis Federation (ITF) said traces of the 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.

2.Viktor Troicki: The Serbian professional tennis player figured in another recent and controversial case. On 25 July 2013, Troicki was banned from playing tennis for 18 months, for failing to provide a blood sample at the Monte-Carlo Masters event. However, the suspension was reduced on appeal to one year, meaning he could play from 15 July 2014. After the Court of Arbitration for Sport announced its decision, Troicki, who had hoped his suspension would be overturned, said that he has “no idea about what to do now or where to go. I hope somehow I will be able to fight back."

Troicki refused to take a blood test claiming he was feeling unwell and had a phobia of needles. 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 an impassioned defence of his friend, calling it an injustice and claiming he had lost faith in the system.

3.Martina Hingis: The Swiss professional tennis player admitted in November 2007 that she had tested positive for cocaine during the summer Wimbledon Championships held that year. But the Swiss, a winner of five grand slam titles and the youngest world No 1 in history when she was 16, maintained her innocence, claiming she had never used the recreational drug. Hingis was banned for two years in January 2008 after an independent tribunal confirmed the doping offence. The International Tennis Federation (ITF) said in a statement that the 27-year-old Swiss would also forfeit the ranking points resulting from the previous year’s Wimbledon championships and $129,481 in prize money. Hingis said she had “no desire to spend the next several years of my life reduced to fighting against the doping officials."

4.Andre Agassi: The American tennis player and former World No. 1 was one of the game’s most dominant players from the early 1990s to the mid-2000s. Agassi is an eight-time grand slam champion and the first male player to win all four major tournaments on three different surfaces - hard, clay and grass. In November 2009, Agassi admitted in his autobiography Open that he used and tested positive for methamphetamine in 1997.

5.Greg Rusedski: The former British number one 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.