Former Manchester City defender Omar Elabdellaoui, now with Galatasaray, returned a positive result after being part of the squad for the international break.
Investigations are currently taking place to see if any team-mates had been in close contact with the 28-year-old. Parkhead duo Kristoffer Ajer and Mohamed Elyounoussi are both in the squad.
Celtic were forced to be without the services of Ryan Christie for the first Old Firm clash of the season after the player was forced into isolation despite testing negative on several occasions.
The midfielder was said to have been in close contact with former Celtic team-mate Stuart Armstrong while on Scotland duty, along with Arsenal’s Kieran Tierney.
Neil Lennon’s side were also hit with the loss of Odsonne Edouard, Nir Bitton and Hatem Elhamed after the same international break with all three testing positive.