Daniel Farke admitted Norwich City's support were right to voice their feelings at the end of a 3-1 Premier League home defeat to Watford.
Many home fans had long since left for the exits at Carrow Road, after Isamila Sarr's second half brace sealed a big win for the Hornets.
But a vocal section of those who remained greeted the final whistle with boos and made their frustration known to Farke on his customary walkabout in the centre circle at the end.
Norwich have now lost their opening five league games of the season for the first time in the club's history.
"The fans were frustrated but I can promise you we are the same," said Farke. "We are self-critical in these moments and it is important to say we are not happy with our defensive behaviour in the key scenes.
"The supporters were excellent. I wanted to fire them up in the press conference (on Friday) because I knew we would need them in this game. They created a top atmosphere in the first half and the second half. They tried everything.
"But if we are there with mistakes we have to be self-critical and say even if there is criticism at the end and the atmosphere goes down we have to do better.
"Obviously the game is finished at 3-1 but even in the difficult periods our supporters were top class.
"But if you produce mistakes then everyone is disappointed. I am not very happy with our defensive behaviour."
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