The Canberra firebrand has emerged as tennis' voice of reason during the COVID-19 outbreak but world No. 3 Dominic Thiem took Kyrgios to task for passing judgement.

Kyrgios criticised Novak Djokovic and Alexander Zverev for taking part in the Adria Tour event, after which several players returned positive coronavirus tests.

Thiem - who was involved in the ill-fated Adria Tour - did admit the 22-year-old German slipped up when he was caught out partying in Monaco days after saying he would spend a fortnight in isolation, in a move Kyrgios lashed as selfish.

"It was his mistake, but I don't understand why a lot of people want to interfere. Kyrgios did a lot of mistakes himself. It would be better for him to come clean instead of criticising others," Thiem told Tiroler Tageszeitung.

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Kyrgios wasted little time in firing back, saying his past misdemeanours pale in comparison to the effect his rivals' could have as a virus continues to run rampant around parts of the globe.

"What are you talking about? Mistakes like smashing rackets? Swearing? Tanking a few matches here or there? Which everyone does?," Kyrgios wrote on Twitter.

"None of you have the intellectual level to even understand where I'm coming from. I'm trying to hold them accountable.

"This just shows what a joke [Thiem], [Zverev], and [Djokovic] think this is, [two] of them partying like [potatoes] during a global pandemic.

"People losing lives, loved ones and friends, and then Thiem standing up for the 'mistake' these guys are the 'top' of our sport. SMH [shaking my head]."

Kyrgios dubbed Djokovic's decision to host a tournament "boneheaded" after it led to Djokovic, his wife and Grigor Dimitrov testing positive to COVID-19.

Boris Becker condemned Kyrgios for calling out Zverev's behaviour, with the latter labelling Becker a "bigger doughnut than I thought" on social media in reply.

However Thiem moved to defend Djokovic, saying he struggles to get a grasp on the criticism being fired at some of tennis' biggest stars.

"He didn't commit a crime. We all made mistakes, but I don't understand all the criticism," Thiem said.

"I've been to Nice and also saw pictures from other cities. It's no different from Belgrade during the tournament. It's too cheap to shoot at Djokovic now."

Tennis Australia chief executive Craig Tiley said in May he was hopeful of the 2020-21 summer of tennis proceeding as planned, amid fears about the virus' threat to the Australian Open.

A spike in coronavirus cases has not helped their cause, however Tiley has said the Open could absorb the financial blow of holding the event without crowds. Officials hope to host the US Open from September 1.