NEW YORK — Roger Federer said Jannik Sinner’s doping case raises questions about whether the current No. 1-ranked tennis player should have been allowed to continue competing until he was absolved of intentionally using an anabolic steroid he tested positive for twice in March.

“It’s not something we want to see in our sport, these types of news, regardless if he did something or not. Or any player did. It’s just noise that we don’t want. I understand the frustration of: Has he been treated the same as others? And I think this is where it comes down to. We all trust pretty much at the end, he didn’t do anything,” Federer said Tuesday in an appearance on the “Today” show to promote a book of photos of him. “But the inconsistency, potentially, that he didn’t have to sit out while they were not 100 percent sure what was going on — I think that’s the question here that needs to be answered.”

Hours later Tuesday night, Federer received a warm ovation from spectators at Arthur Ashe Stadium when he was introduced to the crowd during the second set of the US Open quarterfinal between Aryna Sabalenka and Qinwen Zheng.

Federer smiled and waved as he was shown on the videoboards in the arena.

It was the 20-time Grand Slam champion’s first visit to the venue since he stopped competing. Federer announced his retirement in 2022; he played his last official match at Wimbledon the year before.

He is the last man to win consecutive titles at the US Open, collecting five in a row from 2004 to 2008.

Several top players have been asked about Sinner, who is scheduled to face 2021 US Open champion Daniil Medvedev in the Grand Slam tournament’s quarterfinals on Wednesday.

Rafael Nadal told a Spanish television show Monday he doesn’t think Sinner received preferential treatment.

The International Tennis Integrity Agency said Aug. 20 that it was determined that the banned performance-enhancer inadvertently entered Sinner’s system through a massage from his physiotherapist, and that is why the player was not suspended.

“I understand the frustration of: has he been treated the same as others? … We all trust pretty much at the end, he didn’t do anything. But the inconsistency, potentially, that he didn’t have to sit out while they were not 100% sure what was going on — I think that’s the question here that needs to be answered.”

Roger Federer

Asked about the matter in New York before the US Open began, Novak Djokovic said he gets why some tennis players question whether there’s a double-standard in the sport.

“It’s a tricky situation and it’s the nightmare of every athlete and team, to have these allegations and these problems,” Federer said, adding: “We need to trust the process as well of everyone involved.”

Federer said he spoke recently with Nadal, his longtime on-court rival and off-court friend, who is 38 and has played sparingly the past two seasons because of injuries, including a hip operation last year. He is sitting out the US Open.

There are questions about whether Nadal, who has won 22 Grand Slam trophies, will return to the tour.

“He can do whatever he wants,” Federer said. “He’s been one of the most iconic tennis players we’ve ever had in our sport. … I just hope he can go out on his terms and the way he wants to.”