Nick Kyrgios has questioned world No.3 Dominic Thiem's intellect after being scolded by the Austrian for criticising Alexander Zverev's COVID-19 self-quarantine breach.
Kyrgios has been an outspoken critic of players flaunting social-distancing measures amid the pandemic but Thiem - like Boris Becker - took the Australian star to task for passing public judgement on others.
Thiem - who was involved in Novak Djokovic's ill-fated Adria Tour along with Zverev - did admit that the 22-year-old German erred caught out partying in Monaco just days after saying he would spend a fortnight in isolation.
"It was his mistake, but I don't understand why a lot of people want to interfere," Thiem told Tiroler Tageszeitung.
"Kyrgios did a lot of mistakes himself. It would be better for him to come clean instead of criticising others."
True to recent form, Kyrgios was quick to hit back and said his own past misdemeanors were nothing in comparison to actions that put lives at risk.
"What are you talking about @ThiemDomi ? Mistakes like smashing rackets? Swearing? Tanking a few matches here or there? Which everyone does?," Kyrgios tweeted.
"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, 2 of them partying like potato's 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."
The latest slanging match comes two weeks after Kyrgios condemned Djokovic for a "boneheaded" decision to go ahead with the Adria Tour after the world No.1 and others tested postive for Covid-19.
It's also a week after he labelled Becker a "doughnut" on social media after the tennis legend labelled him a rat for calling out Zverev's behaviour.