Djokovic, the world’s No. 1 player, has declined to reveal his vaccination status and said he was uncertain about playing in the tournament, which he has won nine times. It is especially significant because he is tied with Rafael Nadal and Roger Federer with 20 all-time Grand Slam singles titles. Nadal intends to play in the Australian Open, which runs Jan. 17-30 in Melbourne. Federer will not play, with his future in doubt after having another knee surgery.
