Rangers will be without midfielder Connor Barron for "eight to 12 weeks," Danny Röhl has told Sky Sports News.
He was forced off late on in Tuesday's 2-0 win against Aberdeen with a knee problem, while Dujon Sterling is also out after suffering a hamstring injury.
Sterling, who missed eight months of last season with a ruptured Achilles, could return for their game against Dundee later this month.
"Connor Barron looks really bad at the moment. I think it will be eight to 12 weeks. It's a big injury," Röhl said.
"Dujon could be available for the Dundee game. This is more positive, but still out for the weekend.
"It's a little bit like, since I'm here, we always have injuries.
"We never have the right timing for injuries, but always when you think this is the starting XI, these players could have helped and they are out.
"Oli [Oliver Antman] is back in the training, Joe [Rothwell] is back in the training, but it's not enough to be a straight starter on the squad.
"The two injuries from Tuesday hurt really."
Sterling's latest injury comes after he was arrested following Rangers' 3-1 victory in the Old Firm game against Celtic on Saturday.
The 26-year-old was charged in connection with road traffic offences involving drink driving after police received reports of a one vehicle crash in Glasgow in the early hours of Sunday morning and is expected to appear in court at a later date.
"It will be a lesson for him for his life," Röhl said when asked about the incident.
"I spoke with him very honestly, very directly. I have a really good relationship with him. He is also disappointed about himself. I think this shows a lot.
"If the police are involved, then it's never easy. One of the good things is that nothing happens more, just with the car.
"Now we have to look at what we do and what happens next, I cannot tell you more."
