Ben Gibson and Angus Gunn will not be available for Saturday's Sky Bet Championship meeting with Burnley, according to head coach David Wagner.
Goalkeeper Gunn has picked up a hip injury which will require further screening while Ben Gibson and his partner welcomed a new son this week which saw the defender absent from training.
"Ben Gibson got a son this week, we're happy that everything went well for him, his wife and his son but he wasn't in training this week. Next week, he will be back in training," Wagner explained.
"Angus had some hip problems yesterday in training but he won't be involved. We don't think it's serious but we will have further investigations in London and we hope he will soon be involved in training and matchdays again."
The head coach also noted that Jonathan Rowe, Sam Byram and Przemysław Płacheta are all expected to be out until late in March.
On the signings front, Wagner was pleased that the club have tied down the future of Republic of Ireland international Adam Idah.
He outlined how impressed he has been with the striker's application while also highlighted how he will look to help develop Idah in the future.
"I'm over the moon as well that we could extend his contract. I've worked with a lot of talents in Germany and Adam is a real talent. I like what I've seen, he has space to improve but he has everything to become a very good striker," he said.
"He has had injury problems in the past but I think that this can help you to be mature and to become experienced. He certainly has a lot to give to us in the future."
This is in addition to the return of Christos Tzolis from his loan at FC Twente, as well as Brazilian teenager Marquinhos joining on-loan from Arsenal.
"The recruitment department followed him (Marquinhos) for a long period, he played with Gabby. When the opportunity came up, after losing three wide players, we were able to get him," Wagner added.
"Everything I have seen and heard is good, Gabby will help him settle in here. He's a technical player but with good physicality.
"We spoke about Christos a few weeks ago. There was no clause to bring him but Stuart worked tirelessly to get him back because if he's not starting in Twente but is our player, we want to work with him and educate him for the future.
"Christos has just turned 21, which is still very, very young. He was keen to come here, to re-join us, to help us. And I was keen to have him back too."
On Saturday's opposition, the head coach pointed out how difficult the challenge will be against the league leaders.
Vincent Kompany's men are 17 points clear of the play-off spots and five ahead of Sheffield United in second place.
"They (the players) know Burnley better than I do, they've seen them more. We've prepared them with the information we have.
"We've seen areas we think we can exploit, that's always how football works but they're top of the league for a reason. Bring it on.
"I like challenges. They've only lost two games this season, it speaks for itself. It's at our stadium, we need the energy and atmosphere that makes you think 'Today, something special can happen'."