Middlesbrough manager Tony Pulis was unhappy with the decision to send off Rudy Gestede after his side lost at Carrow Road.
Gestede was shown a straight red card in the 28th minute for a mistimed tackle on Grant Hanley, having already been booked for accidentally catching Alex Tettey with a high boot.
The Canaries went on to record what was a comfortable win, despite the tight scoreline, but Pulis felt referee Michael Jones’s decision changed the course of the game.
“For the first one, I don’t think it was a booking at all,” he said. “Rudy couldn’t see their player and there was absolutely no intent.
“For the second one, I have seen challenges in the Premier League this week that were 10 times worse than that and the players haven’t been sent off.
“I am very disappointed about what was a game-changing decision by the referee. I thought it was a good game until the sending off but I don’t want to focus too much on that.
“We created two good chances before the red card and one good one after it but we didn’t take them and that is very disappointing. You will generally have problems if you miss chances like we did.”
The only goal came moments before the break as the Canaries finally got their noses in front in a game which had been an even contest until the flashpoint.
After another long period of possession, the patient hosts worked the ball across the face of the area to German midfielder Tom Trybull, who sent a low shot into the bottom corner.
Norwich City: Gunn, Hanley, Zimmermann, Klose, Reed, Tettey, Trybull (Leitner 60), Lewis, Maddison (Vrancic 72), Oliveira, Murphy (Hernandez 86). Unused substitutes: Watkins, Stiepermann, Srbeny, McGovern.
Middlesbrough: Randolph, Shotton, Ayala, Gibson, Friend, Clayton (Assombalonga 82), Leadbitter, Downing, Traore, Gestede, Bamford (Howson 63). Unused substitutes: Konstantopoulos, Cranie, Fry, Harrison, Besic.
Referee: M Jones (Chester).