Injured Celtic duo Scott Brown and Shaun Maloney are still three weeks away from returning to training.
The key pair have been out of action for over two months as they struggle with niggling injuries.
Brown was forced to undergo further ankle surgery, while Maloney has been troubled with an Achilles problem.
Celtic boss Tony Mowbray is hoping to welcome back the pair in January
"I'd maybe expect them back in full training in around three weeks," Mowbray
told the club's official website.
Better news on the injury front for Mowbray is that Koki Mizuno, who has not featured for more than three months, has already returned to training after undergoing knee surgery.
"On a more positive note, Koki Mizuno has recovered from a knee operation and trained this week," added Mowbray.
Meanwhile, South Korea midfielder Ki Sung-Yueng could make his debut in Sunday's Old Firm clash with Rangers, while Darren O'Dea should also be available for selection after returning from his loan spell at Reading.