Celtic have reported negative Covid-19 tests for their players on international duty and at their training ground after Neil Lennon's side were hit with a double blow.
Ryan Christie has been ruled out of the visit of Rangers on October 17 after being instructed to self-isolate along with former Hoops team-mate Kieran Tierney after their Scotland colleague Stuart Armstrong tested positive. Two members of the Scotland medical staff are also self-isolating.
Christie's 14-day isolation comes on the back of striker Odsonne Edouard testing positive for the virus on Tuesday while on France Under-21 duty.
Edouard must self-isolate for at least 10 days – potentially longer if he develops symptoms during the first week – and his participation in the derby clash is also in doubt.
The 22-year-old played for Celtic during their 2-0 win over St Johnstone on Sunday but so far nobody else in the squad has been infected with the coronavirus.
Celtic wrote on Twitter: "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."
Edouard earlier allayed any fears over his health with a message on social media.
He wrote on Twitter: "Thank you all for your messages of support! I'm fine and I would come back stronger. Take care of yourself and your family."