David Wagner expects Friday's starting centre-half pairing of Grant Hanley and Ben Gibson to miss out on Monday's visit of Rotherham United.
Both players picked up injuries in the 2-0 win at Blackburn Rovers on Friday, with skipper Hanley stretchered off in the first half.
He was replaced by Andrew Omobamidele before Gibson, who had taken over the captain's duties, then also succumbed to a muscle injury in the second half.
It adds to the loss of Kenny McLean who Wagner says will be out for an extended period after picking up an injury against Sheffield United.
"Grant has an Achilles injury. How serious it is, we have to see, he will have a scan. Ben pulled his hamstring and both will be out for sure for Monday," Wagner said.
Despite that double blow, the head coach was keen to remain positive ahead of Monday's fixture, highlighting the performances of those who stepped up at Ewood Park.
He's also looking forward to welcoming Isaac Hayden and Sam Byram back into the fold.
"Luckily we have Isaac and Sam back in training, Sam since two weeks ago and Isaac one week. If the weekend goes well, they might be able to help us Monday, or at the latest Middlesbrough."
"All of the other guys who stepped up against Blackburn have done fantastic, Onel (Hernández) is back, Liam (Gibbs) was good. Andrew came on and was switched on from the first second, he was a wall in defence. And Lungi (Jacob Sørensen) played fantastic as well."
There'll be a familiar face in the Rotherham United ranks with Jordan Hugill making his first appearance at Carrow Road since leaving to join the Millers in the January transfer window.
While Wagner's time with Hugill was brief, he spoke highly of the former Canary.
"I'm very happy for Jordan that he's settled in very well and it only shows that he made the right move. He's a great character as well, it will be good to see him back," he explained.
"We will try everything to keep him quiet on Monday but it's not just about him. They're a good team, they've picked up some good results, beating West Brom speaks for itself.
"We know we have to win our home games. We won't do it on our own, we'll need every City supporter at their best if we want to make it into the play-offs."