Thiem, speaking at his Thiem's 7 tournament in Kitzbuhel, Austria, leapt to the defence of fellow Adria Tour participant Alexander Zverev after Kyrgios was among those who criticised the German for being caught on camera partying again after having promised to go into quarantine.
Thiem said: "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."
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Kyrgios responded to that on Twitter with a cutting riposte to Thiem, seemingly incredulous that he and other players are still taking part in events amid the coronavirus pandemic.
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"What are you talking about @ThiemDomi? Mistakes like smashing rackets? Swearing? Tanking a few matches here or there? Which everyone does?" Kyrgios said.
"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 @ThiemDomi @AlexZverev & @DjokerNole 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.
Thiem, who left Novak Djokovic's controversial Adria Tour event to briefly appear at Patrick Mouratoglou's Ultimate Tennis Showdown, is now hosting his own exhibition with Kyrgios having now accused him of thinking the coronavirus crisis is "a joke".
This latest online spat comes two weeks after Kyrgios condemned Djokovic for what he called a "boneheaded" decision to go ahead with the Adria Tour after the world number one and other top players tested positive for Covid-19.
The Australian also got into a fiery debate on Twitter with Boris Becker, branding him a 'doughnut' after the German legend called him a "rat" for condemning his compatriot Zverev's behaviour.
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