Maria Sharapova may be spared the maximum four-year ban for failing a drug test if she can prove she has a condition which requires the treatment she took, an anti-doping expert has said.
Five-time grand slam winner Sharapova announced on Monday she had tested positive for a substance called meldonium at this year's Australian Open.
Meldonium was placed on the banned list by the World Anti-Doping Agency (WADA) at the beginning of the year, having been part of its monitoring programme throughout 2015.
Sharapova, who said she had legally taken the medication throughout her career to deal with health issues including an irregular heartbeat, will be provisionally suspended from tennis later this week and could face a ban of up to four years.
However, former UK Sport anti-doping chief Michele Verroken says the 28-year-old Russian could receive some leniency if she can prove she needed to take the drug for medical purposes.
Verroken told BBC Radio Five Live: "We were all notified back in 2014 that it (meldonium) would be part of the monitoring programme. We were given notice end of September, beginning of October (2015) that the change to the list would include this now being a banned substance rather than just being monitored.
"Certainly for all the doctors that I work with, I know that they will have been checking the list and one hopes anyone advising athletes would make sure they are updating themselves specifically at that time in order to allow for the application for what they call a therapeutic-use exemption, if that's applicable, but if not, to change the treatment.
"Now the challenge facing Maria Sharapova and her team is to bring forward the diagnostic evidence that she has a condition that required the prescription of this treatment.
"But if she can actually prove that she may get some leniency from the disciplinary panel."
Sharapova says she accepts "full responsibility'' for her actions but former British number one Jo Durie believes the Russian might have expected more help from people around her.
Durie does not believe the former world number one is a drugs cheat either, saying it was a "very big mistake" that she is going to pay the price for.
Durie said: "Everyone's shocked and it's just one big mistake isn't it from Maria and her team, who didn't pick this up.
"Maria has stood up and said ultimately that it's her responsibility, she's the athlete and she should check. But when you get to the top of your sport you are surrounded by a team of people who really should be advising you and checking and doing all these things.
"I just think it's very sad that this has happened.
"I think that Maria is, in my opinion, an honest person who's made a very big mistake; she's going to pay for it.
"I don't think she's a drugs cheat, I really don't, I think she's been caught out with something she thought was perfectly okay to take and then didn't check the lists."