Ronny Deila fears that Emilio Izaguirre may need surgery on a fractured finger.
The defender picked up the injury during the 1-0 Europa League defeat from Inter Milan and missed Sunday’s win over Aberdeen.
Izaguirre will miss tonight’s match against St Johnstone with Deila having to hold back the defender for his own good.
“Izaguirre is out, even though he wants to play,” the Celtic boss told the Evening Times. “We don’t take any chances with him. If he gets injured again, they may need to operate, and we don’t want that.”
Deila added: “Kris Commons won’t make this game, either, but he should be okay for Sunday. It’s just a nerve injury.
“Stuart Armstrong will be okay for this game. It was cramp on Sunday. It was a sign he’s not strong enough yet.”
Almost since he arrived Deila has talked up Celtic’s prospects of winning the treble.
Winning their next three matches, against Dundee United in both cup competitions after tonight’s clash with St Johnstone, would go a long way to achieving that goal with Deila realistic about those prospects.
“I think we are the best team, if we don’t get to our full potential then I will be disappointed but the cup is the cup,” the Celtic boss explained.
“You can get a red card, or be very unlucky but if the performance is bad and we lose because we are not good enough then I will be a little bit disappointed because I believe we can do it.
“I didn’t say we were going to win the Europa League because that was not realistic but it is realistic to win the treble.
“I know that it is up to us. If we don’t do it then we are not good enough but high goals gets high demands and good performances and this group can handle it.”