Nick Kyrgios and Dan Evans are among the tennis stars to take a swipe at Novak Djokovic after three players tested positive for COVID-19 after participating in the Adria Tour exhibition tournament organised by the world No.1.
Grigor Dimitrov, Borna Coric and Viktor Troicki have all announced that they have COVID-19.
The tournament, which also had top names such as Dominic Thiem and Alexander Zverev, was held in Belgrade and Zadar in Croatia and the players were also pictured playing basketball and dancing together without following social distancing protocols - although they did not break any government protocols.
Djokovic's own coronavirus test results will be revealed late on Tuesday evening (AEST) after which he will address the public, Serbian media reported on Monday.
Australian star Kyrgios condemned the decision to hold Djokovic's charity event.
Kyrgios took to Twitter on Monday night to remind fellow professionals, in his own blunt way, that the COVID-19 pandemic that has shut down tennis is not to be taken lightly.
"Boneheaded decision to go ahead with the 'exhibition'," he posted.
"Speedy recovery fellas, but that's what happens when you disregard all protocols. This IS NOT A JOKE."
British No.1 Evans echoed those sentiments.
"I don't think he should be having a players' party and dancing all over each other," Evans said before Jamie Murray's behind-closed-doors 'Battle of the Brits' tournament that begins in London on Tuesday.
"Two very good tennis players have tested positive. He should feel some responsibility in his event and how it's transpired, really.
"It's very unfortunate that Grigor has it and Coric has it but you strip it back, is it a surprise? I think that's the question we should all ask."
American tennis great Chris Evert also criticised the organisers for the lack of social-distancing, saying "... total physical contact, no face masks, even the fans were without masks.. I don't get it."
The positive tests raise serious concerns for the governing bodies of tennis in their bid to restart the sport after the professional game was shut down in March.
Last week the ATP and the WTA issued revised calendars for the resumption of the circuit from August while organisers of the US Open said the grand slam will be staged without fans starting on August 31.