The 28-year-old US-based Russian, who has won all four of the tennis Grand Slams, said she had failed to realise that meldonium, the heart medicine she had first taken in 2006 for “several health issues”, had been put onto the World Anti-Doping Agency’s banned list on January 1 this year.

Her composed demeanour at the press conference, and her wry aside about the “fairly ugly” carpet of the downtown Los Angeles hotel in which it took place, certainly stood in her favour.

And the reaction from within her sport was a broadly supportive one in which Sharapova - who is now suspended and awaiting a potential four-year ban - was praised for her “honesty”.

Sharapova’s sporting nemesis, Serena Williams, told a New York City press conference: “I think most people were surprised and shocked by Maria but at the same time most people were happy that she was just upfront and very honest and showed a lot of courage to admit to what she had done and what she had neglected to look at.”

It may be that Sharapova was telling the truth, the whole truth and nothing but the truth. It may be that she required meldonium for a range of problems including a family history of diabetes and an “irregular” heart scans.

Performance at elite level is certainly not proscribed by cardiac irregularities. A few years back I helped Britain’s Olympic 400 metres silver medallist and double European champion Roger Black write an autobiography in which he revealed that he had been diagnosed as a teenager with an irregular heartbeat, or heart murmur, caused by a congenitally defective valve.

So it can happen. But how extraordinary that so many elite athletes – 2.2 per cent of a sample of 8,320 undertaken by the World Anti-Doping Agency last year - were also using meldonium. And how extraordinary that 17 per cent of Russian athletes tested showed traces of the substance that is designed to improve blood flow in their system.

Martina Navratilova, whose Grand Slam record makes Sharapova’s list of five victories appear modest, initially tweeted: “it seems 2 me to be an honest  mistake”.

But then the former Czech player appeared to modify her position: “Good that Maria Sharapova stepped up and told the truth about having been taking Meldonium. I don't believe the reasons though- eg diabetes?”

Navratilova’s doubts have been voiced in a different form by Craig Pickering, Britain’s Olympic sprinter and now bobsleigh competitor, who has written in his blog:

“Let’s cut right to the chase. I would bet my life savings that Sharapova was taking this medication because of its purported performance enhancing effects. The same reason as a number of other athletes, including the 2013 World Champion over 1500m Abeba Aregawi, were taking it, and now have positive tests to their name.

“Here’s the thing though - I don’t care if she was taking it for the performance enhancing effects. For the vast majority of the time that Sharapova was taking the drug, the substance wasn’t banned. It has only been banned since January 1st, a period of two and half months. If it isn’t banned, then athletes are allowed to take it.”

This, surely, is the view from the arena. I’ve heard the same from numerous athletes over the years. Pickering goes on to point out the numerous substances elite athletes take to gain an edge which are not on the banned list, such as caffeine or nicotine, or a range of supplements.

The grey area extends further, of course. For example, creatine, which became widely available in the 1990s and is still widely used today, mimics many of the effects of anabolic steroids in terms of building muscle mass an enabling higher levels of performance in anaerobic work. But creatine is not on the banned list.

For example. If you are found to have taken EPO (erythropoietin) or one of its cousins to boost the level of oxygen-carrying blood cells in your body, you face a doping ban. As you do if you take out your own blood, store it, then restore it to boost your oxygen-carrying capacity. But if you have been able to afford to train at altitude, or indeed if you happen to live at altitude, where the same enriching process takes place naturally, you should gain the same advantage when you return to sea level without being in danger of any ban.

Is this fair? Not crystal clear, is it?

The discussion forks at this point. One path follows concerns that young athletes - whether this was the case with Sharapova or not - might be being prescribed medication they don’t need in order to enhance performance.

Pickering’s cogent argument drew this response from the Daily Telegraph’s chief sports writer, Paul Hayward, who tweeted: “but Craig, in pursuit of edge you can't have 18-year-olds starting 10 years on a heavy angina drug banned in the US?”

It’s a serious concern. In the wake of Sharapova’s ambiguous statement about first taking meldonium in 2006, which suggested she has been doing so for a decade, the Latvian manufacturers of the medicine, Grindeks, told the Associated Press that standard treatment involved courses of four-to-six weeks, perhaps two or three times a year.

Could Sharapova, or others, have been putting their health at risk by not observing those guidelines?

The second path follows this argument, applied to athletes – whether Sharapova is among them or not – who knowingly seek to enhance their performance by taking medicinal products which are not medically justified. What do you lose when you gain by these means?

As Pliny once wrote – and for all I know, he might have written it more than once – “Multi famam, conscientiam pauci verentur” – “Many fear their reputation, few their conscience.”

Meanwhile the baffling element of the Sharapova case remains. Assuming there was no deliberate attempt to take a banned substance and attempt to get away with it at one of the four pre-eminent events on the tennis calendar – how could she and/or her team have failed to check the annual adjustment to the WADA list of banned substances?

No wonder Richard Pound, the former WADA President, described it this week as “reckless beyond description."

Whatever the reason, ultimate responsibility lies with the athlete for whatever finds its way into their system. How harshly Sharapova will be dealt with remains to be seen. But surely, even if Russia makes it to Rio 2016, she can’t.