World No. 19 Grigor Dimitrov and No. 33 Borna Coric both announced they had tested positive for Covid-19 after playing in the Adria Tour tournament in Zadar, Croatia, which was organized by Djokovic and swiftly canceled following Dimitrov's positive test.
Djokovic's agent Elena Cappellaro told CNN that the Serb has been tested and is awaiting the results, while his fitness coach Marco Panichi has tested positive but is showing no symptoms.
The world No. 1 was set to play Andrey Rublev in Sunday's final in Zadar, Croatia, before the cancellation was announced.
"Boneheaded decision to go ahead with the 'exhibition,'" Australian Nick Kyrgios wrote on Twitter in response to Coric's positive test.
"Speedy recovery fellas, but that's what happens when you disregard all protocols. This IS NOT A JOKE."
The event was the second leg of a four-part exhibition series that is raising money for charity and taking place in the Balkans while the ATP Tour is postponed until August 14.
"I don't understand ... no safe distancing, total physical contact, no face masks, even the fans were without masks," tennis great Chris Evert wrote on Twitter in response to photos of players in close physical contact over the course of the event.
According to the Croatian Institute of Public Health, there have been 2,317 confirmed cases of the coronavirus in Croatia and 107 deaths.
Photo caption: Dimitrov and Coric pose for a photo during their Adria Tour semifinal match in Zadar, Croatia.