Norwich face an anxious wait to discover the extent of Josh Sargent's ankle injury.
City were 4-0 winners at Huddersfield on Saturday but the win was marred by the American forward limping off.
Sargent charged down Terriers goalkeeper Lee Nicholls to put the visitors ahead on 11 minutes but stayed down after Nicholls' last-ditch tackle.
Canaries boss David Wagner told BBC Radio Norfolk: "Unfortunately it looks like a serious ankle injury."
The 23-year-old has started the Championship season in fine form and scored for the third straight game in the comfortable victory.