How do you persuade the world number one player to accept a ban for something he believes he is innocent of?
That was the challenge facing Sinner’s team.
To understand the extent of that we have to rewind to August when an independent tribunal cleared him of wrongdoing.
It accepted Sinner’s explanation that traces of clostebol – a banned anabolic steroid – had entered his system through inadvertent contamination from his physio during a massage.
Wada, while not challenging the tribunal’s overall decision, appealed against the panel’s ruling that Sinner “bore no fault or negligence”.
However, this would have carried a ban of “one to two years” at the Court of Arbitration for Sport (Cas).
Although Wada initially called for this punishment publicly, eventually its officials came to feel this would not be the right outcome.
With time ticking before the Cas hearing in April, Wada made two approaches to Sinner’s team for the case resolution agreement.
The first attempt was rebuffed as Sinner’s team wanted to submit the full defence case first.
That was handed over on 31 January, and in early February the first “concrete discussions” began after the second approach.
But with Sinner always sure of his innocence and confident he would face no ban, would he accept a three-month suspension?
His lawyer Singer said it was “quite tricky” to convince Sinner to take the offer.
“When I was saying ‘well, look, maybe we should settle for three months’, he was saying ‘well, why would we do that if the first independent tribunal found it was no ban at all, why would I accept three months now?’,” Singer said.
“My advice was ‘one never knows what’s going to happen at a hearing, we know that Wada are pushing for a year, if we don’t accept their offer then they will go to court looking for a year and who knows what those three judges could do’.
“So the possibility of three months, in my view, was a good possibility.”
Why the deal was made
Wada felt the independent tribunal should have punished Sinner for strict liability – that he was ultimately responsible for failing the two drugs tests.
Its officials felt pursuing a suspension was key in defending the “important principle that athletes do in fact bear responsibility for the actions of their entourage”.
So why was Wada happy to offer Sinner a three-month ban?
Wada’s general counsel Ross Wenzel said there wasn’t a “fundamental change” in how the agency viewed the case, but it came down to what it considered fair.
“This was a case that was a million miles away from doping,” Wenzel told BBC Sport.
“The scientific feedback that we received was that this could not be a case of intentional doping, including micro-dosing.”
Had the case gone to Cas, the outcome would have either been a ban of at least a year or Sinner being cleared.
“I’m not sure that a sanction of 12 months in this case – if we’d have forced the tribunal into that position – or a case of ‘no fault’ would have been a good outcome,” said Wenzel.
“One would have compromised an important principle under the code. The other one, in our view, would have been an unduly harsh sanction.”
Case resolutions have been allowed since 2021, and Wenzel said Wada had since struck 67 agreements.
The code is set to change from 2027, meaning cases where players have failed tests but were deemed not to be at fault – like Sinner – could be punished from a reprimand to a two-year ban.
“In two years, Sinner would simply have had a slap on the wrist,” one source from an anti-doping organisation told BBC Sport.