“I have made a mistake with the Adria Tour and also with the birthday party afterwards,” Zverev told dpa from New York after losing to Andy Murray in the early rounds of the Western & Southern Open.

“I have made a huge mistake and so I can also understand people [being annoyed].”

Zverev, 23, insisted he had not endangered anyone other than himself by playing in Novak Djokovic’s mini-tour organized in June.

He has tested negative for the coronavirus seven times, “but clearly that wasn’t the smartest thing in the world,” he added.

The Adria Tour was scrapped after a slew of positive tests for the coronavirus, Djokovic among them.

Players did not observe social distancing or a hygiene protocol and were pictured partying a nightclub. No local rules were broken at the time.

Zverev also admitted he angered organizers of an invitational tournament in Berlin by pulling out at short-notice.

“After the Adria Tour, my management had said: ‘better stay home’,” Zverev said. “Of course I was negative. I had tested negative seven times after the Adria Tour that I can prove.

“But in Berlin there were also a few fans again and I simply didn’t want to take another risk.”