Maria Sharapova has been "reckless beyond description" in failing a drugs test, according to former World Anti-Doping Agency chief Dick Pound.
The cost to Sharapova of her positive test for banned substance meldonium became clearer on Tuesday as three major sponsors distanced themselves from the tennis superstar.
The Russian dropped the bombshell at a press conference in Los Angeles on Monday and is now waiting to find out what sanction she will face.
Speaking to BBC Sport, Pound said: "Running a $30m business depends on you staying eligible to play tennis. You are taking something on a list, which you have known about for four months. I am sorry, that is a big mistake - of course she should have known.
"She is taking something that is not generally permitted in her country of residence [the United States] for medical purposes, so she says, so there must be a doctor following this."
Meldonium was added to the WADA banned list at the start of 2016. Pound added: "Any time there is a change to the list, notice is given on 30 September prior to the change. You have October, November, December to get off what you are doing.
"All the tennis players were given notification of it and she has a medical team somewhere. That is reckless beyond description."
With regard to Sharapova's sponsors, Nike acted swiftly, suspending its contract with the five-time grand slam champion, while watchmaker Tag Heuer and luxury car brand Porsche followed suit.
A statement from the sportswear giant 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."
Tag Heuer has severed ties altogether, while Porsche, who signed Sharapova as its first global endorser in 2013, has postponed its sponsorship.
The Russian has been the highest-earning female athlete in the world for the last 11 years, with her off-court endorsements dwarfing her income from prize money. According to Forbes, the 28-year-old earned #21million in 2015.
Among her other sponsors, Evian ostensibly stuck by her while cosmetics firm Avon declined to comment.
With the assembled media expecting a retirement announcement on Monday, Sharapova revealed she had tested positive for meldonium following her quarter-final defeat against Serena Williams at the Australian Open in January.
Meldonium, which Sharapova said she had legally taken for 10 years, was added to banned list following, according to WADA, "evidence of its use by athletes with the intention of enhancing performance".
Sharapova claimed she had not read the updated list of banned substances sent to athletes in December and took "full responsibility" for her actions.
She is one of a number of Russian athletes to have fallen foul of the new rules on meldonium, and revelations about the drug since her announcement have raised more questions than answers.
Use of the drug was monitored by WADA last year following suspicions. A study has reportedly shown it was present in the system of 17 per cent of Russians tested and 2.2% of all athletes.
Nick Wojek, head of science and medicine at UK Anti-Doping, said: "It's not a drug used in western Europe and America as a therapeutic drug, so you'd think that's a very high percentage [2.2%].
"I think it would infer, although you couldn't categorically say one way or the other, that there would be some misuse within that number, hence why it's gone on to the banned list.
"If you're using a drug for a non-therapeutic reason then for me that's an unethical use of that particular drug."
Sharapova claimed she was prescribed meldonium, also known as mildronate, by her doctor in 2006 to deal with health issues such as an irregular heartbeat and a history of diabetes in her family.
"We have decided to suspend our relationship with Maria while the investigation continues." - Nike statement
One of the other major questions arising is why Sharapova was prescribed a medicine that is not licensed in the USA, where she has been based since the age of seven.
The drug company that manufacturers it, meanwhile, has reportedly stated it should normally only be taken for between four and six weeks at a time.
Wojek said: "From the [patient information] leaflet it would suggest they did recommend it's only for a six-week period to help ease the lack of blood flow - depending on what the medical condition was and the dosage being used.
"You'd have to look at the specifics but, generally speaking, if the information leaflet is saying six weeks, [to be prescribed it for 10 years] would be surprising."
The International Tennis Federation [ITF] said Sharapova had been informed of the positive test on March 2 and would be provisionally suspended from 12 March.
Sharapova has waived the right to have her B sample tested and she and her team will instead hope everything she has done so far will limit the sanction she is given.
The next step is for an independent tribunal to be established to hear the case. A decision would be expected around two weeks after the hearing.
Subject: Maria Sharapova Fails Drugs Test 
