Serbia's Novak Djokovic holds the Norman Brookes Challenge Cup after defeating Russia's Daniil Medvedev in the men's singles final at the Australian Open tennis championship in Melbourne, Australia, Sunday, February 21, 2021. [AP, Andy Brownbill]
Australian authorities scrambled on Sunday to file a legal defence of their decision to bar entry to tennis world number one Novak Djokovic over his COVID-19 vaccination status, as the Serbian superstar spent his fourth day in immigration detention.