Tennis star Nick Kyrgios has slammed rival Alexander Zverev after the young-gun German broke a promise to self-isolate after being exposed to COVID-19.

An apologetic Zverev said six days ago he would go into self-isolation after joining in the Novak Djokovic-led Adria Tour – which has since produced a cluster of coronavirus cases and caused outrage for the lack of social distancing on display.

Djokovic, his wife Jelena, coach Goran Ivanisevic and top tennis players Grigor Dimitrov, Borna Coric and Viktor Troicki have all tested positive to the virus since joining in the charity event in Croatia early in June.

“I have just received the news that my team and I have tested negative for COVID-19,” Zverev wrote on Twitter.

“I deeply apologise to anyone that I have potentially put at risk by playing this tour. I will proceed to follow the self-isolating guidelines advised by our doctors. As added precaution, my team and I will continue with regular testing.

“I wish everyone who has tested positive a speedy recovery. Stay safe.”

Tweet from @BenRothenberg

But the 23-year-old was filmed partying in a room full of people at a private club in Monaco at the weekend. He has been widely condemned online – including in an expletive-laden spray from Kyrgios.

“I wake up and I see more controversial things happening all over the world. One that stuck out for me was seeing ‘Sacha’ Zverev again man, again, again, how selfish can you be?” Kyrgios said.

“If you have the audacity to f—ing put out a tweet that you made your management write on your behalf saying you’re going to self-isolate for 14 days and apologising to the f—ing general public for putting their health at risk, at least have the [commitment] to stay inside for 14 days, my god.

“Jesus man, p–sing me off, this tennis world is p–sing me off, seriously how selfish can you all get?”

See Kyrgios’ full response (warning: offensive language)

Tweet from @BenRothenberg

It’s not Kyrgios’ first coronavirus rant. Last week, he condemned Djokovic’s charity event – reminding fellow professionals that the COVID-19 pandemic that has shut down tennis is not to be taken lightly.

“Boneheaded decision to go ahead with the ‘exhibition’,” the Australian posted.

“Speedy recovery fellas, but that’s what happens when you disregard all protocols. This IS NOT A JOKE.”

Zverev is yet to comment, despite multiple social media photos and videos emerging of him in Monaco. Some have already been taken down.

Elsewhere, Kyrgios has also been vocal in his disgruntlement with the United States Tennis Association and ATP Tour for their plans to host the US Open in New York City at the end of August.

Tweet from @NickKyrgios