Novak Djokovic's coach Goran Ivanisevic is the latest person involved with the world number one's Adria Tour to test positive for coronavirus.
Former Wimbledon champion Ivanisevic, 48, was the director of the Croatian leg of the event organised by Djokovic.
Serbia's Djokovic apologised after becoming the fourth player - along with Grigor Dimitrov, Viktor Troicki and Borna Coric - to test positive.
Ivanisevic urged people he has been in contact with to "take extra care". The Croat said he is "feeling good" and does not have any symptoms.
He added: "I will continue to self-isolate as I have been doing already. I wish everyone who got infected a speedy recovery."