Jannik Sinner fired his fitness trainer and physiotherapist because of his two positive steroid tests in March and said at his US Open news conference that he knew he was innocent but still worried about what the case’s outcome would be until finding out he wouldn’t be suspended.

“It has been a very tough moment for me and my team,” Sinner said at the site of the year’s last Grand Slam tournament, where he is the No.1-seeded man.

“It still is.”

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Play begins on Tuesday (AEST) at Flushing Meadows.

Sinner is scheduled to meet first round opponent Mackie McDonald, an American ranked 140th, on Wednesday (AEST).

McDonald got into the US Open field when Rafael Nadal withdrew earlier this month.

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“It’s not ideal,” Sinner said with a bit of a chuckle when he was asked about the timing of this week’s news of his doping case.

He also called the outcome “a relief.”

Sinner is a 23-year-old Italian who moved up to No.1 in the ATP rankings for the first time in June and is considered one of the leaders of the next group of male tennis stars who will succeed the ‘Big Three’ of Roger Federer, Nadal and Novak Djokovic.

Sinner’s first Grand Slam trophy came in January at the Australian Open.

He is 48-5 with a tour leading five titles in 2024 and tuned up for the US Open by winning the hard court Cincinnati Open on Tuesday (AEST).

The next day, the International Tennis Integrity Agency announced that Sinner failed two drug tests in March — one during a tournament in Indian Wells, California, and one eight days later — but that it was determined the banned anabolic steroid Clostebol entered his system unintentionally through a massage from his physiotherapist, Giacomo Naldi.

Sinner’s defence was that his fitness trainer, Umberto Ferrara, purchased an over the counter spray that contained Clostebol in Italy, then gave it to Naldi, who used it on a cut finger.

Sinner said Naldi then gave him a massage.

The player Sinner beat in the Cincinnati final, Frances Tiafoe, was asked about the news.

“He’s an incredible player, and, you know, (governing) bodies made a decision. They went and did that, he’s cleared to play. That’s pretty much what I have to say about it,” Tiafoe said.

“All the best to him in the US Open.”