Tennis icon Rafael Nadal has made it clear he does not believe Jannik Sinner would have intentionally taken a performance-enhancing substance after the doping saga surrounding the World No.1.

On the eve of the US Open, it emerged that Sinner, 23, had tested positive for a banned substance in March. He was eventually cleared and has maintained his innocence.

“If he hasn't been sanctioned, it's because the judge has clearly seen that he hasn't doped. I don't think they have judged him as innocent simply because he is the world #1.”

Speaking ahead of the US Open, where Sinner is facing Tommy Paul in the fourth round, he admitted he had “sleepless nights” over the case. He told ESPN: "It had an impact because I was often ill, I didn't feel much energy on the court, I think we saw this at Wimbledon for example.

"I went through sleepless nights thinking about it, and had some physical problems perhaps related to this. There were very difficult moments on the court, I didn't feel like myself, I wasn't happy.

"The process was very long and with time you feel a greater weight, the great wait for the end, the arrival of the results, it wasn't an easy period, but now I'm happy.

"But now I just want to move on, I'm not saying that everything will be ok straight away. but I hope to feel happy on the court again.".