Brendan Rodgers is expecting to see Kris Ajer back in action before the winter break.
The defender suffered a fractured eye socket in the 0-0 draw at Livingston on November 11 but will resume full training tomorrow.
Celtic have six matches to be negotiated over the next fortnight with Rodgers looking to have as many options available as possible.
Jozo Simunovic has played alongside Filip Benkovic in the last two matches but the likely return of Ajer will be a welcome boost for the away matches at Easter Road, Pittodrie and Ibrox.
“Kris starts training with the squad next week,” Rodgers told The Sun. “I’m not sure if he will wear a mask. It will be his preference.
“He won’t be available for Salzburg. That’s too soon. Kris will train and then we will maybe see over the next few weeks.”
Dedryck Boyata is having his hamstring strain assessed on a daily basis with the matches at Pittodrie on December 26 and three days later at Ibrox in mind.
If the Benkovic/Simunovic partnership stands up over the coming games Rodgers will be in no rush to break up that pairing but having Ajer and Simunovic available will be a welcome Plan B.