Novak Djokovic's coach, former Wimbledon champion Goran Ivanisevic, has confirmed he has tested positive for coronavirus.
The Croatian, who triumphed at the All England Club in 2001, had come out in defence of the Serbian over his organisation of the ill-fated Adria Tour.
The event had to be cancelled after one of the participants, Grigor Dimitrov, confirmed he had tested positive.
Meanwhile, this year's Davis Cup Finals has been postponed until 2021.
The event will now take place in Madrid in the week commencing November 22, 2021.
International Tennis Federation David Haggerty said on the Davis Cup website: "This is a tough decision to have to make, but delivering an international team event on this scale while guaranteeing the health and safety of all involved ultimately poses too great a risk.
"It is a complex undertaking and we have made the decision now to provide certainty for players, national associations and fans. We look forward to continuing our partnership with Kosmos Tennis in order to deliver a fantastic competition next year."