Liam Gibbs and Onel Hernández are set to spend a couple of months on the sidelines with injury, according to head coach Johannes Hoff Thorup.
Gibbs picked up an injury in training ahead of the win against Watford while Hernández was replaced just minutes after coming on against the Hornets.
"Not really positive (Gibbs), I think we're talking return to play in maybe 10 weeks' time. It's what we were hoping it wasn't, very disappointing for him but also us," Hoff Thorup said ahead of the Derby County fixture.
We wanted him to challenge to become a regular starter for us. He's a good player, has the physical capacity to cover a lot of ground.
"Onel is the same, we're talking 10 weeks or more. It didn't seem that serious in the game but we took him out and could see that he was struggling with full speed and full power. It's also a long one."
However, there was a positive update on Anis Ben Slimane who has returned to full training after missing the last two games.
"Back in the team, he's been on the pitch the whole week so he should be back. We would prefer to have Gibbs too because we don't want to be short in midfield."
Hoff Thorup also spoke about the two pieces of signing news this week.
First, Kellen Fisher agreed a new contract with the club for the next four years while Tony Roberts has been named as Paul Clements' successor as head of goalkeeping for the club.
"We gave Kellen minutes in pre-season as a midfielder because he'll cover right-back for us in an inverted role. Even though he was not playing, he's done everything he could every day in training to make that position competitive," the Dane explained.
"He's playing with confidence and intensity in his game. He's still young, there'll be games where that isn't the case but he's ready to take the next steps in his career.
"We're delighted to add Tony, it was our top priority. We appreciate the support from the academy. Dec (Rudd) will also travel with us tomorrow as well as Tony. We went for what we thought was the most ambitious candidate and thankfully we got that.
"The same as the goalkeeper coach, we've taken our time to find someone who is the right fit for the first-team coach, the right mentality. We're getting closer, next week could be a busy one."
Last time out, City scored four in an emphatic home win against Tom Cleverley's side.
It was the best performance of the season according to Hoff Thorup who hopes to see his side build on it further.
"The good moments we had in that game were the best we've had this season. It felt like we could score a goal at any time in the game - I didn't have that feeling at Oxford.
"There's definitely some improvement areas for us, but it's been important for me to tell the guys that they've done well. We were not satisfied at Swansea, we created moments and chances, the result could have been different and we had to highlight that but overall it was not good."
This weekend, City will go to Pride Park where Derby County have won all three of their league fixtures so far this season.
The Rams are also managed by Norfolk native and City fan Paul Warne.
"Let's see how big a fan he is tomorrow," Hoff Thorup said jokingly.
"We have to make sure we go there tomorrow and ensure they won't keep that home record. It's a strong team, they have good discipline, they get in to a compact shape really quick.
"We need to focus on our team, our performance and I know they will be fully prepared for when we come tomorrow.
"I've just heard how many fans are travelling to the game tomorrow (over 2,800) which is so impressive. When we need that extra motivation, that power, we can get that from the crowd. It's a big advantage for us to have that support in difficult moments.