Dimitrov lost to Coric in the Croatian leg of the Adria Tour on Saturday, with the former confirming he returned a positive test on Sunday.
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That led to the Zadar final between Novak Djokovic and Andrey Rublev being cancelled, with Coric then revealing on Monday he has also tested positive.
Alexander Zverev, Marin Cilic and Rublev have tested negative for COVID-19, while Djokovic’s results are not yet known.
As the fallout continues, Kyrgios was one of the vocal critics on Twitter, while Zverev has apologised for taking part in the event.
Men's world number one Djokovic organised the Adria Tour as a charity event designated to be contested over four legs across the former Yugoslavia.
Austria's Thiem won the opening leg in Belgrade, where a capacity 4,000 crowd turned up on each day at Djokovic's tennis centre by the Danube river.
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With both Serbia and Croatia easing lockdown measures weeks before the event, players were not obliged to observe social distancing rules in either country and were seen embracing at the net at the end of their matches.
Fans in Croatia, however, were subject to the rules and had to keep their distance, meaning that the 9,000-capacity Visnjik tennis complex was half-full for the event.
The third leg due in Montenegro on June 27 and 28 was scrapped last week over coronavirus concerns while the final leg, scheduled for July 3 and 4 in Bosnia's Banja Luka, is now likely to be called off.
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A statement from the Adria Tour on Sunday said: "As a precaution and to protect the health of all participants and visitors, the organisers of Adria Team have decided to cancel the grand finale of the tennis spectacle planned for tonight.
At all times we have strictly followed the epidemiological measures in place with the countries where the Adria Tour was organised. None of the people involved in the organisation and who have been in contact with Grigor have any symptoms. However, we are in close contact with health authorities to insure that all people who were in contact with Grigor Dimitrov will be tested tonight.
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