Spanish media have been calling attention to the lengthy ban handed to local skater Laura Barquero after she tested positive for the anabolic Clostebol, the same substance that earned Sinner a three-month ban after a settlement reached between WADA and the Italian tennis player on Saturday.
The deal has also been roundly criticised by many of his fellow tennis professionals.
WADA said that while both cases involved the same substance, the specific facts related to Barquero's case were "very different" to Sinner's.
In an email sent to The Associated Press, WADA said: "The fundamental difference between the two cases is that Ms Barquero's version of how the substance entered her system was unconvincing in light of the evidence, such that the circumstances remained unknown as far as WADA was concerned.
"In contrast, in the Sinner case, the evidence clearly confirmed the athlete's explanation as outlined in the first instance decision."
Barquero first tested positive for Clostebol during the 2022 Winter Olympics, then again in January 2023 in an out-of-competition test carried out by the International Skating Union.
WADA eventually entered into a "case resolution agreement" in which the athlete was suspended for six years. They said the agreement was accepted and signed by WADA, the ISU and the athlete herself.
"If Ms Barquero did not agree with the proposed sanction, she was not obliged to sign the case resolution agreement and was free to take the case forward for hearing at CAS," WADA said.
The agency had sought to ban Sinner, a three-time Grand Slam champion, for at least one year. They had challenged a decision last year by the International Tennis Integrity Agency not to suspend Sinner for what the ITIA judged was accidental contamination of the banned anabolic steroid last March.
WADA formally withdrew their appeal saying they accepted the athlete's explanation for the cause of the violation, and that Sinner did not intend to cheat.
Sinner's explanation was that trace amounts of Clostebol in his doping sample was due to a massage from a trainer who used the substance after cutting his own finger.
Barquero was expected to make a public comment later on Monday. Her Instagram account republished several stories calling attention to the discrepancy in the punishment given to her and to Sinner.
