Tennis great John McEnroe has hit back over a long-running controversy surrounding Rafael Nadal, regarding the amount of time the 22-time grand slam champion is afforded by umpires on his serve.

Nadal takes on Italy's Fabio Fognini in the second round of the US Open in New York on Thursday (Friday AEST), after overcoming Australia's Rinky Hijikata in the first round.

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However, the issue of whether the Spaniard is afforded preferential treatment by umpires has reared its head again at Flushing Meadows.

Back at the Australian Open in January, Canada's Denis Shapovalov labelled the chair umpire "corrupt" during his match with Nadal after complaining about the amount of time the Spaniard took to serve and play.

Again at the US Open, a reporter asked if Nadal was leaving "some kind of a shadow" on his legacy by "not following the serve clock rule", citing previous comments from McEnroe to support the notion.

McEnroe did speak about the issue at the French Open.

Nadal responded to the reporter's question at the US Open by labelling the issue a "joke", before suggesting in a tongue-in-cheek manner that he would have a chat to McEnroe about it.

Addressing the drama as part of Eurosport's US Open coverage, McEnroe said he had not spoken to Nadal and wondered why he'd been dragged into the debate.

“Why did they throw me under the bus? We haven't had that talk (with Nadal) but let me just add that… he didn’t let me finish, whoever the dumb journalist was,” McEnroe explained.

“Rafa Nadal is entitled to do whatever the hell he wants, that’s part of why you get as good as [Nadal is], you’ve got to deal with that.

“And it’s not up to him. We all know that he’s been doing this for the past 10 to 15 years. There's nothing new to that. It’s not his call - it’s the umpire's.”

McEnroe then went on to claim that “no one pays attention” to the 25-second serve rule, before going on record to stress that he doesn't think it's tarnished Nadal's legacy.

“And by the way I think it’s BS anyway, that [rule]. No one pays attention to that. It should be automatic if you’re actually going to do it, right?" McEnroe said.

“And when do they turn it on? Is it at the end of the point? Is it when they get to the towel? Is it when the crowd comes down?

“This guy... now Nadal thinks I’m saying his legacy’s been stained because he takes too much time."

Rafa Nadal looking to book spot in third round

Nadal's second round match against Fognini comes after the 36-year-old's hard-fought victory against Hijikata in the first round.

The Spaniard survived a bit of scare from the young Aussie, who stunned the tennis world after winning the first set.

Hijikata, the World No.198, was given no chance against Nadal at Arthur Ashe Stadium on Tuesday, but caused a huge boilover when he took the first 6-4 against the 22-time grand slam champion.

Hijikata broke an out-of-sorts Nadal in the seventh game to take a 4-3 lead, before holding on to claim the opening set in stunning scenes.

The 21-year-old Australian roared with delight and threw his arms in the air on a number of occasions, with the centre court crowd in New York getting behind the massive Aussie underdog.

Thankfully for Nadal and his legion of fans, regular transmission resumed in the second set before he went on to win the match 4-6 6-2 6-3 6-3 to advance to the second round.

However the Spaniard needed five match points to secure the match in the fourth set, with Hijikata showing immense fight and courage on the biggest stage in tennis.

It marked Nadal's first win at the US Open since 2019. He opted not to travel to America in 2020 before. afoot injury ruled him out of the hard-court grand slam last year.

Nadal, who is a four-time champion in New York, is looking to take advantage of Novak Djokovic's absence and win his 23rd major.

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