World tennis No. 1 Novak Djokovic was back in practice hours after winning a court challenge to remain in Australia on Monday. Djokovic posted on Twitter a photograph of himself on a court at the Rod Laver Arena at Melbourne Park with a caption thanking the judge who released him from immigration detention over his vaccine exemption status. The Serbian tennis player remained focused on his bid for a record 21st Grand Slam win in Melbourne, his tweet said. Djokovic’s family hailed the “biggest victory” of his life, and said the battle to overturn the cancellation of his visa would only make him stronger at the Australian Open. Fans in Australia and back home in Serbia welcomed the news that Judge Anthony Kelly had found the Australian federal government’s decision to cancel Djokovic’s visa to be “unreasonable,” because the player was not given enough time to speak to tennis organizers …