Grant Hanley will miss at least the next six weeks of action after picking up a quadricep injury in training.
Hanley has captained the Canaries in all of the Sky Bet Championship fixtures so far and the news comes as a blow to Daniel Farke and his team.
Speaking at his pre-match press conference, Farke said: "Grant Hanley will be out for the next six weeks. He has a rare injury with his quadricep.
"It's bad news that Grant is out but the young lads can step up now. I trust all of the lads. Christoph [Zimmermann] has shown he is capable to perform.
"The same goes with Ben [Godfrey]. He is developing really well and did well at Cardiff and was solid against Ipswich."
Hanley's absence also means the captain's armband must be exchanged but Farke says he's not concerned.
"We have a core group of leaders. Timm [Klose], Alex [Tettey], Ivo [Pinto], Christoph - they can all wear the armband so I'm not concerned who is captain in Grant's absence."
Farke also confirmed that Ivo Pinto will be unavailable for the Middlesbrough game with a hamstring injury.
Elsewhere, Farke confirmed the news that Kenny McLean and Louis Thompson will return to action at the end of September.
"It's good news with them. After Ipswich, Louis was concerned but he has recovered quite well. He should be back in training towards the end of month.
"The same goes with Kenny. He could be back in training towards the end of next week or potentially the week after. I'm looking forward to having them both back."
There was also positive news delivered on the fitness of Mario Vrancic who has been out of action since the end of last season.
"He's available and back in the mix. His last game was at the end of April. It's not so easy to come into the game rhythm. But he's back and available for tomorrow."