Arsenal defender Kieran Tierney is set to miss the Premier League clash with Manchester City after being told he must self-isolate due to a coronavirus case in the Scotland squad.
Southampton midfielder Stuart Armstrong returned a positive result for a test conducted on Tuesday, the Scottish Football Association confirmed in a statement.
Armstrong must quarantine for 10 days, meaning he will miss Scotland's Euro 2020 play-off semi-final against Israel and the Nations League matches with Slovakia and the Czech Republic.
Tierney, Ryan Christie and two of Scotland's support staff have been identified as close contacts of Armstrong, meaning they must now self-isolate for 14 days.
They will also sit out the coming international matches, while Tierney will miss the meeting between Arsenal and City on October 17.
Celtic midfielder Christie will be forced to sit out the Old Firm clash with Rangers on the same day.
Scotland head coach Steve Clarke said: "While this is obviously disappointing news the most important thing is the health and safety of the individuals involved and the wider group.
"As soon as we were informed of the positive test, the Chief Medical Consultant immediately contacted the Scottish Government's clinical adviser, who in turn alerted the local Health Protection Team.
"We have informed the respective clubs from whom we have borrowed the players and backroom staff and we now have to prepare for a huge match ahead tomorrow."