World No. Jannik Sinner found backing from the legendary Rafael Nadal over his doping row. Nadal said he doesn't think Sinner intended to use a banned substance and that the Italian tennis sensation didn't receive preferential treatment when he was cleared of doping after testing positive twice in March for trace amounts of an anabolic steroid.

"I trust that he wasn't punished because those who judged this case determined quite clearly that there was nothing to punish. ... I don't believe the sentence has anything to do with him being No 1 in the world," 22-time major champion Nadal said in an interview with "El Hormiguero" on Monday.

The International Tennis Integrity Agency (ITIA) announced on August 20 that Jannik Sinner's positive test for a banned performance-enhancing substance was deemed unintentional, resulting from a massage by his physiotherapist. Consequently, Sinner avoided suspension.

When questioned about the incident in New York ahead of the US Open, Novak Djokovic acknowledged understanding why some players might perceive a double standard in tennis, implying that the ITIA's decision may have raised eyebrows among his peers.

Nadal, who sat out the US Open, said he has no reason to doubt the ITIA's decision. "I believe in someone's good faith. I know Sinner; I don't believe that Sinner wanted to dope. In the end, justice is justice, and I believe in justice," Nadal said."I believe in the bodies that have to make decisions and that they do it based on what they believe is right."

Meanwhile, Sinner made the last eight of the US Open for the second time by seeing off 14th seed Tommy Paul 7-6 (7/3), 7-6 (7/5), 6-1 in the fourth round match on Tuesday. He will take face Russia's former World No.1 Daniil Medvedev for a spot in the semi-final. Medvedev, the 2021 champion and runner-up to Djokovic last year, outclassed Portugal's Nuno Borges 6-0, 6-1, 6-3 to reach the quarter-finals for the fifth time in six years.

With no Carloz Alcaraz and Novak Djokovic remaining in the tournament - both knocked out - the winner of the Sinner vs Medvedev quarters could well very decide the champion of this year's US Open.