NEW YORK -- Rafael Nadal has defended Jannik Sinner after the world No. 1 tested positive for a banned substance but avoided punishment, saying the Italian would never have considered doping and he was not judged differently just because he is the top-ranked player.

In March, Sinner tested positive for the steroid clostebol, which can be used to build muscle mass, but was cleared by a tribunal after they learned his physio applied a spray to a cut on his own hand before carrying out treatments on the Italian.

Sinner arrived at the US Open with players alleging double standards when he was cleared of wrongdoing where others had been provisionally suspended for similar positive tests, but Nadal said the antidoping organizations must be trusted.

"I have a virtue or a deficit, which is that in the end I usually believe in people's good faith. I know Sinner, I don't believe that Sinner has ever wanted to dope," Nadal told Spanish television show "El Hormiguero."

"I don't think we have to like it only when it is resolved in the way we think. In the end, justice is justice and I believe in justice.

"I believe in the bodies that have to make decisions and that really make them based on what they believe is right."

The International Tennis Integrity Agency (ITIA) cleared Sinner after he failed two drug tests in March, but he has always maintained his innocence, saying the amount of clostebol found in his system was less than a billionth of a gram.

The ITIA is an independent body established in 2021 by the governing bodies of the sport.

Novak Djokovic called for "clear protocols" and "standardized" approaches to doping cases while Australian Nick Kyrgios said Sinner should have been banned no matter the manner of doping, whether it was "accidental or planned."

However, Nadal said the authorities had not given Sinner preferential treatment.

"I'm totally confident that if he has not been sanctioned it is because those who have had to judge this case have seen very clearly that there were no sanctions to be imposed," added Nadal, who skipped the US Open due to fitness concerns.

"I do not believe that because he is Sinner he will not be sanctioned and because he is someone else he will be sanctioned. I really believe it and I am convinced of it.

"Afterwards, the opinion of others is also totally respectable. But, well, this is my opinion."

Top seed Sinner is scheduled to face American Tommy Paul in the US Open fourth round later Monday.