Dimitrov, ranked No. 19 and a three-time Grand Slam semifinalist, is the highest-profile current player to say he has the virus. His announcement Sunday on his Instagram page comes at the end of a week when the US Open said it would go forward.
The professional tennis tours have been suspended since March and are planning to resume in August.
Dimitrov also played a match against Borna Coric in Croatia, at the Adriatic resort of Zadar, on Saturday in the second leg of the exhibition series. After the match, he complained about fatigue. He said in his post that he was tested in Monaco.
Organisers said Sunday the exhibition has now been cancelled. Djokovic had been scheduled to play Russia’s Andrey Rublev in the final.
Besides Djokovic, other leading players participated in the events, including Dominic Thiem in Belgrade and Alexander Zverev in both tournaments.
Some of the sport’s top names, including defending men’s champion Rafael Nadal along with top-ranked Ash Barty have expressed reservations about heading somewhere that was a hot spot for the COVID-19 outbreak. Others expressed an eagerness to return to action.
The US Open normally is the fourth and final Grand Slam tournament of each season but would be the second major of 2020, following the Australian Open, which concluded in early February.