He said he received his positive PCR result after attending a tennis event in Belgrade, but said he received a negative rapid antigen test before the event.
He wrote: “I was asymptomatic and felt good, and I had not received the notification of a positive PCR test result until after that event.
“The next day, on 18 December I was at my tennis centre in Belgrade to fulfil a long-standing commitment for a L’Equipe interview and photoshoot. I cancelled all other events except for the L’Equipe interview.
“I felt obliged to go ahead and conduct the L’Equipe interview as I didn’t want to let the journalist down, but did ensure I socially distanced and wore a mask except when my photograph was being taken.
“While I went home after the interview to isolate for the required period, on reflection, this was an error of judgement and I accept that I should have rescheduled this commitment.”