Australian Nick Kyrgios has labelled the decision to go ahead with the Adria Tour as "boneheaded" after Borna Coric became the second tennis player to confirm that he tested positive for the coronavirus on Monday.
Dimitrov played a match against Coric on Saturday in the second leg of the series. World No. 33 Coric confirmed his positive test on Twitter.
"Hi everyone, I wanted to inform you all that I tested positive for Covid-19," the Croatian said. "I want to make sure anyone who has been in contact with me during the last few days gets tested!
"I am really sorry for any harm I might have caused! I'm feeling well and don't have any symptoms. Please stay safe and healthy! Lots of love to all!
Kyrgios, who was vocal after Dimitrov tested positive, condemned the decision to run the tournament during the pandemic.
"Boneheaded decision to go ahead with the 'exhibition' speedy recovery fellas, but that's what happens when you disregard all protocols," he wrote on Twitter. "This IS NOT A JOKE."
Djokovic's fitness coach Marco Panichi has also tested positive, Serbian daily Sportski Zurnal reported, quoting Croatia's health institute.
The tournament witnessed packed stands during the opening leg in Belgrade, players hugging at the net, posing for pictures together and dancing at clubs.
With both Serbia and Croatia easing lockdown measures weeks before the event, players were not obliged to observe social distancing rules in either country.
"It is recommended that anyone who has been in close contact for more than 10 minutes with the tennis player be advised to self-isolate for 14 days and to contact their doctor," the event organisers said in a statement.
Information from Reuters was also included in this report.