Grand Slam champions are among the 47 players in hard lockdown after four positive tests for Covid-19 emerged from two of the charter flights bringing players, staff, officials and media to Australia for the first tennis major of the season, AP reports.

Some players were angry at being classified as close contacts merely for being on board those flights with people who later tested positive and, therefore, forced into a harsher quarantine than the broader group of players who’ll be allowed out of their rooms to practice for up to five hours per day.

But local health authorities have said all players were warned of the risks in advance and any players considering bending the rules have been warned. Breach quarantine regulations and there’s the prospect of heavy fines or being moved to a more secure quarantine complex with police stationed at their doors.