“All WADA are really doing here is saying we accept that it is unintentional but you bear, or did bear, a certain degree of fault or negligence for what’s happened … we say that you, as the athlete, bear the ultimate responsibility – which is strict liability – and we say, therefore, you have demonstrated fault and negligence in your actions.

“And then we’re going to look at now [what] we say is between a mid- to high-range level of fault or negligence, and that’s why they’re seeking [a ban of] one to two years.

“One year would be deemed to be at the high end of the low fault standard. Zero to 12 [months] is the range for low fault.”

Sinner tested positive to clostebol at Indian Wells in March, and returned a second positive test from a urine sample out of competition. Clostebol is an anabolic agent on WADA’s prohibited list.

Sinner said the drug entered his system through a massage given by his physiotherapist.

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Sinner, who became the world No.1 in June, has had a successful season, winning the Australian Open, the US Open, the season-ending ATP Finals, the Davis Cup with Italy, and reaching the semis of Wimbledon and Roland-Garros. He forfeited the prizemoney and rankings points he received for reaching the Indian Wells semi-finals in California eight months ago.

The circumstances of his case, and his exoneration by the tennis body due to “inadvertent contamination”, became public in August on the eve of the US Open.

Sinner’s defence rested on evidence that his support team bought an over-the-counter product in Italy known as Troferdermin, a lotion or spray that contained clostebol.

According to the findings, Sinner’s fitness trainer Umberto Ferrara bought the substance and gave it to physiotherapist Giacomo Naldi, who used it on his own skin to treat a small wound.

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“That support team member applied the spray between 5 and 13 March, during which they also provided daily massages and sports therapy to Sinner, resulting in unknowing transdermal contamination,” the International Tennis Integrity Agency said.

Its tribunal concluded: “there is no suggestion that the tiny concentration in his system would have had any performance-enhancing effect”.

Sinner was disappointed by WADA’s appeal.

“I have nothing to hide, and as I have done throughout the summer, I will co-operate fully with the appeal process and provide whatever may be needed to prove my innocence once again,” he said in September.

At the weekend, after Italy won the Davis Cup, Sinner said: “Of course I had some ups and downs, and whoever knows me was emotionally a bit down, a bit also heartbroken. But sometimes life gives you difficulties and you just have to stand for it.”

While Fuller predicted that Sinner would be banned, he said CAS could be “persuaded” by the International Tennis Integrity Agency findings.

“CAS are not bound by anything the ITF has ruled. They will examine this de novo [looking at evidence afresh],” he said. “CAS will look at all of the evidence, the reasoning that’s been applied, the submissions made by the parties … and they could rule in a completely different manner to the first instance hearing.

“Conversely, they could look at the first instance decision carefully and be persuaded by it. They’re not bound by the decision, but what has been handed down can often be highly persuasive.

“The test applied at the CAS for an athlete’s level of diligence is one of ‘utmost caution’.”

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