The Dutchman suffered the injury late on during the victory over Everton and Norwich are waiting to discover the extent of the problem.
Norwich have been dealt a blow in their Premier League survival battle with goalkeeper Tim Krul set for a spell on the sidelines because of a shoulder problem.
Dutchman Krul suffered the injury late on during the victory over Everton on Saturday and Norwich are awaiting confirmation of how long he will be unavailable.
“Tim Krul is out. He hurt his shoulder, the ACL joints, in the last minute of the Everton win,” said boss Dean Smith, whose side travel to relegation rivals Watford on Friday night where Angus Gunn is expected to deputise in goal.
“I am not sure on the time with him at the moment. He went to see a consultant yesterday, so I am waiting for the feedback from our medical staff to give me some time on it.
“He will be a big loss as we saw when he missed the two games against Arsenal and Crystal Palace, but when those big players come out of the team and are a loss then it is an opportunity for others.”
Smith is confident Gunn can make the most of another chance to stake his own claim for the Norwich number one jersey.
“Gunny (Angus Gunn) was disappointed with the results that we had in the two games that he played in,” said Smith.
“He has been working hard to get that opportunity back again and it has presented itself now, so he knows he has got to go and play well.
“Gunny also knows that we have got Mick McGovern also who is pushing him in training and Jon McCracken has been pushing the two of them as well.
“We have got four goalkeepers who are all pushing each other at the moment, so Gunny knows he has got to come in and keep his place now.”
Norwich have no other fresh injury concerns, with full-backs Max Aarons and Brandon Williams both recovered after being forced off against Everton while midfielder Kenny McLean is back available following his Covid-19 issues.
Smith feels the win over Everton – following which the Merseyside club sacked manager Rafael Benitez – has given everyone a “spring in their step” as they aim to pull themselves out of the bottom three with victory at Vicarage Road on Friday night.
“It has certainly lifted the place,” said former Aston Villa boss Smith, who replaced Daniel Farke in mid-November.
“I said before the Everton game to the players that it wasn’t quite the ‘be all and end all’ game, but it was getting that way.
“Getting that victory was really important for us and probably takes a little bit more pressure off of us now going into this Watford game – but we all know how important this game is and that it can do a lot for both teams.
“It gives us the opportunity to try and climb out of the relegation places, for however long, and it also gives Watford the opportunity to try and get away from us.”
Norwich have played more matches than all of their relegation rivals – with bottom club Burnley currently holding four in hand, but only two points behind.
“I think it is disjointed across the league table because of something like 21 postponements throughout the festive period and January, such has been Covid and injuries for teams,” said Smith.
“It is going to be disjointed for a while and until they all catch up, it is going to be that way unfortunately.”
