Celtic have been left "disappointed and frustrated" after Ryan Christie was forced into a fortnight's self-isolation.
The midfielder was told he and Arsenal's Kieran Tierney must isolate following Stuart Armstrong's positive Covid-19 test at the Scotland camp.
He will now miss the club's next fixture against Rangers on October 17.
Celtic insist their primary concern is with the health and wellbeing of all involved, with two Scotland backroom members also isolating.
But a club statement admits regret that another issue has arisen during the international break following Odsonne Edouard testing positive for the virus on Tuesday.
Celtic revealed all other players - either at Lennoxtown or with national teams - returned negative results on Wednesday.
A statement said: "Clearly we are disappointed and frustrated to learn of today’s news, however, our over-riding concern is of course the health of the players and staff concerned.
"It is of course disappointing that this has arisen during the international break but it is something which shows the many challenges clubs currently face.
"Celtic’s rigorous testing programme continues.
"The Celtic squad based at Lennoxtown have all again returned negative test results today.
"In addition all other players currently on international duty, outwith Odsonne as reported yesterday, have reported negative tests."
Celtic stars Callum McGregor and Greg Taylor are also with the Scotland squad but have not been told to quarantine.
