Eight Aberdeen players are self-isolating and will miss three Scottish Premiership matches after two squad members tested positive for Covid-19.
One of the initial cases was confirmed by a follow-up NHS test and the other player is awaiting further results.
Both are asymptomatic but are self-isolating, along with six players who were "in close proximity".
All eight men were in an Aberdeen bar - linked to the city's Covid-19 spike - on Saturday after the loss to Rangers.
Chairman Dave Cormack said the club would investigate and have reminded players of their responsibilities.
And a Scottish Government spokesperson said they were "disappointed by the actions of these individuals who have put at risk the return of professional football in Scotland".
Minister for public health and sport Joe Fitzpatrick has called a meeting with the Scottish FA and SPFL on Friday to discuss the situation after what a government statement calls "a clear breach of the rules".
With the city already locked down due to a cluster of cases, Aberdeen's training was cancelled on Thursday.
However, Saturday's Scottish Premiership trip to face St Johnstone will go ahead.
The first player to test positive will self-isolate until 15 August, with the remaining seven doing so until 19 August.
All eight are set to miss matches against Hamilton Academical and Celtic, as well as Saturday's game in Perth.
"Given the efforts of everyone at the club and our investment in protecting our most valuable assets, this is a bitter blow," said Cormack.
"It is also a harsh reminder of the severity and speed of spread of this virus. We now have to focus on preparing for Saturday's game under extremely difficult circumstances."
Cormack appealed for "patience" with the affected players, pointed out that everyone "is prone to errors of judgement" and stressed that "it is all about how we respond to something we wish had not happened".
Restrictions were imposed in Aberdeen on Wednesday, with the number of new cases in the city having risen to 79 - with more expected in the coming days.
Pubs and restaurants have been closed since 17:00 BST on Wednesday, while people have been told not to visit the city and those living there face travel restrictions.
Aberdeen are scheduled to host Hamilton Academical at Pittodrie next Wednesday and, as things stand, that game is unaffected.
The Scottish government had previously said matches are not at risk amid the lockdown because clubs are "within a sporting bubble" and are being tested twice a week.
Rod Petrie, chair of Scottish football's Joint Response Group, said the decision not to call off Saturday's game came after consultation with the authorities.
"The Scottish government's instruction was clear and unequivocal, as was our support of that instruction," Petrie said. "It is imperative everyone adheres to public health advice."
On Tuesday, it was announced that there were no positive results from the latest round of coronavirus testing among Scottish clubs.
Three have now been returned since football resumed - one of which came from an Aberdeen player at the start of July, although that later was confirmed to be a false positive.