With marathon battle against Roger Federer as example, Nick Kyrgios declares tennis the "toughest" sport in the world

Australian tennis player Nick Kyrgios reckons tennis is by far the "toughest" sport in the world.

Kyrgios believes tennis surpasses the National Rugby League (NRL) as the toughest sport in the world, a claim he substantiated by pointing to his marathon match against tennis ace Roger Federer at the 2017 Miami Open as an example.

Federer and Kyrgios played a humdinger of a match in the semifinals, touted to be the 2017 ATP Match of the Year. While Federer saved set points, Kyrgios saved match points before the Swiss maestro ultimately went on to win the epic battle with a 7-6(9), 6-7(9), 7-6(5) scoreline after a grueling three hours and 11 minutes.

Taking to Instagram on Wednesday, Kyrgios responded to claims that the NRL was the toughest sport in the world, saying that he wasn't kidding when he meant tennis is the toughest sport in the world.

"Tennis is by far the toughest sport in the world. I'm not even kidding," Kyrgios wrote in response to a question if NRL is the toughest sport.

Nick Kyrgios Instagram story

He added a screenshot from his epic Miami Open encounter against Roger Federer to prove his point, adding:

"Anyone who thinks tennis is easy, goodluck. Match went for about 3 and a half hours," he wrote, along with a laughing emoticon.

Nick Kyrgios and Roger Federer at Miami Open in 2017.

Nick Kyrgios and Roger Federer have met seven times on tour, with the Swiss ace winning six times. Kyrgios' lone win over Federer came in 2015 at the Madrid Masters, where the Australian won 6-7(2) 7-6(5) 7-6(12).

Nick Kyrgios racing against time to recover from injury

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The Australian, currently ranked 22 in the world, is currently recovering from a knee injury. An MRI on his knee revealed a small tear and a cyst in his lateral meniscus, which required immediate arthroscopic surgery to heal.

The knee injury forced him to withdraw from the Australian Open and the tennis player subsequently underwent surgery.

The Australian had intended to make his return to the ATP Tour at the Sunshine Double. But despite his manager Daniel Horsfall passing on encouraging news early in February, it seems Kyrgios' recovery has not progressed enough to enable him to compete in the Indian Wells and Miami Masters.

The World No. 22 reached the quarterfinals of the Indian Wells Masters in 2022, where he lost in a closely contested encounter against Rafael Nadal. Subsequently, Nick Kyrgios suffered a third-round exit at the Miami Masters, losing to Jannik Sinner in straight sets.