Novak Djokovic is unlikely to defend his Australian Open title due to the vaccine policy, according to an interview with the player's father.
Authorities in Melbourne are requiring players to be fully vaccinated for the January showpiece, which Djokovic has won nine times.
The Serb's current vaccination status is unknown, but he has previously expressed his ambivalence about the treatment for Covid-19, which he contracted last year.
Djokovic's father Srdjan was quoted on Serbian television casting doubt as to whether his son would bid for a 21st Grand Slam title in Australia.
The news website B92 reported Srdjan Djokovic's claim that the conditions set by tournament organisers were 'blackmail'.
"As far as vaccines and non-vaccines are concerned, it is the personal right of each of us whether we will be vaccinated or not. No one has the right to enter into our intimacy.