Maria Sharapova has turned to Facebook to clarify her use of the drug meldonium.
She denies missing five warnings that the drug was becoming a banned substance before testing positive at the Australian Open.
In a Facebook post, the tennis champion said she was “determined to fight back” against the misreporting of facts on the case.
The International Tennis Federation and WTA alerted players five times in December to the banned list for 2016.
In her dramatic press conference last Monday, Sharapova only mentioned failing to click on a link on an email linking to the documents on December 22.
And she insisted the other missed opportunities were not ones she could necessarily have been expected to take, posting a picture of a complicated wallet card detailing banned substances.
The 28-year-old wrote: “This document had thousands of words on it, many of them technical, in small print.
“Should I have studied it? Yes. But if you saw this document, you would know what I mean.
“I make no excuses for not knowing about the ban. I already told you about the December 22, 2015 email I received.
“Its subject line was ‘Main Changes to the Tennis Anti-Doping Program for 2016’. I should have paid more attention to it.
“But the other ‘communications’? They were buried in newsletters, websites, or handouts.”
As an example, Sharapova cited an email on December 18 that would have required clicking through a number of links to find the information.
However, this email was not one of the five warnings cited by the ITF and WTA.
Sharapova, who knew the drug as mildronate, also addressed comments from the manufacturer that it was only designed to be taken in courses of between four and six weeks.
That has been cited by some as suspicious given the Russian said she had been taking it, as prescribed by her doctor, for 10 years.
But she indicated she had only used it intermittently, in line with the manufacturer’s guidelines, saying: “I didn’t take the medicine every day.
“I took it the way my doctor recommended I take it and I took it in the low doses recommended.”
Sharapova will have a chance to put her case forward at a preliminary hearing later this month before an independent tribunal hears the case and decides on possible sanctions.
“I look forward to the ITF hearing at which time they will receive my detailed medical records,” she said.
Sharapova’s message came on the same day WADA confirmed there have been 99 positive tests for meldonium since the drug was added to its banned list in January.
Sharapova again received support from the chairman and chief executive of her racket sponsor, Head, who issued a statement backing the athlete and criticising WADA for black-listing the substance.
World number two Andy Murray thinks Sharapova must be suspended.
“Clearly, if you are taking performance-enhancing drugs and you fail a drugs test, you have to get suspended,” he said.
“I find it strange that there’s a prescription drug used for heart conditions and so many athletes competing at the top level of their sport would have that condition. That sounds a bit off to me.”