Head Coach Aitor Karanka gave his reaction after Wednesday night's defeat to Millwall in the Sky Bet Championship.
Blues were beaten in the capital with goals from Jed Wallace and Ben Thompson.
It was only the second time Blues have tasted defeat away to Millwall since 1996.
Speaking to the media via Zoom at The Den, Karanka offered his thoughts on the encounter.
"An individual mistake has punished us a lot. In our situation to concede a goal like that after two minutes is difficult to take. We had chances in the first-half and were really good when we could have gone down.
"We were in the game in the second-half and we were going forward, being aggressive and attacking but then we didn't defend well and conceded the second one. I can't say anything bad because losing 2-0 and in our situation, the players were fighting until the last whistle. Everything depends on us, we need to win games.
"We have to look at us, look at our work and I said to the players to keep believing.
"If I do not believe it is impossible for the players to believe. We have to keep believing together.
"We have to keep working and that starts tomorrow at the training ground, analysing the game and then preparing for the following game on Saturday."
Karanka also explained why Sam Cosgrove was absent from the clash.
"Sam twisted his ankle yesterday and I don't think he will be ready for Saturday."