Eighteen-time Grand Slam champion Martina Navratilova has claimed that she hopes that Maria Sharapova made an "honest mistake" by taking a banned substance.
Sharapova announced on Monday that she failed a drug test after losing to Serena Williams at the Australian Open in January.
The five-time Grand Slam champion told the press that meldonium, which she claimed she has taken as prescribed medicine for the past 10 years, was found in her system.
The substance was added to the World Anti-Doping Agency's list of performance-enhancing drugs at the start of 2016.
In response to the admission, Navratilova tweeted: "Hold your horses everyone- about Maria- I don't have all the facts, I hope it's an honest mistake,stuff was legal as far as I know till 2015."
Sharapova will be provisionally suspended by the International Tennis Federation from March 12, and is facing a four-year ban.
