Newcastle's Premier League game with Aston Villa on Friday is under threat due to an outbreak of coronavirus cases, according to British media reports.
Newcastle have closed their training ground and it is not expected to re-open until Wednesday at the earliest, The Guardian said.
Magpies manager Steve Bruce had already cancelled training on Sunday after four players and a member of the backroom staff tested positive for the virus last week.
According to The Daily Telegraph, the club learned that more players tested positive when the latest batch of results were returned on Monday.
The whole first team squad and staff have been told to self-isolate at home.
Bruce was already without five first team players for last Friday's 2-0 win over Crystal Palace.
No Premier League match has been called off since football resumed following the March lockdown.
Premier League authorities have said before for a game to be postponed it would require 14 players to be affected.
However, if the team is able to field 11 players plus three substitutes the game should go ahead.
The fixture schedule is already a hectic one with many managers blaming a higher-than-usual rate of injuries on that.
According to the Telegraph, the possibility of the players turning up solely for training on Wednesday without entering the buildings is being considered.
The city of Newcastle itself will enter the tier three restriction band on Wednesday when the latest lockdown ends -- the highest allocated by the Government.