Novak Djokovic is making sure he's ready for next week's Australian Open despite uncertainty he'll be allowed to remain in the country -- hitting practice courts hard Down Under on Tuesday.
The tennis superstar was spotted getting in a lengthy workout at Rod Laver Arena in Melbourne ... hitting balls and sweating just six days away from the start of the big tournament.
Of course, Djokovic needs all the practice he can get ... considering he was cooped up in a hotel for nearly a week after Australian authorities tried to bar him from entering the country.