Arsene Wenger has warned that Arsenal are at a pivotal moment of the season and has told his under-performing players to take a good look at themselves.
The Gunners boss says the mistakes made to concede the goals - two of which were own goals - in the 4-3 defeat by Blackburn on Saturday were down to basic errors.
Asked what lay behind the leaky defence, Wenger said: "A lack of concentration, a lack of communication, a lack of co-ordination and individual urgency. When you score an own goal, you have to look at yourself. It is never completely out of your reach where you have no chance at all. All the rest, you have to look at yourself."
He added: "The Blackburn game is very disappointing and frustrating. I must say that the disappointments and frustrations are huge. We feel that we have given this game away, not that we have lost the game. There is nothing worse in our job than having that feeling."
Wenger said the Gunners were now at a point that could prove decisive for their whole season.
He added: "I personally want to focus on the positives because there is huge potential in this team. We had 22 shots on goal, 61% of the possession. Our season depends now on how well we respond to this disappointment and how quickly we can cut out the mistakes we made on Saturday by giving away goals that we should never give away."
Wenger will field a youthful line-up alongside some older heads as Arsenal aim to avoid an unthinkable shock in the Carling Cup third round against Shrewsbury on Tuesday night.
Wenger confirmed he will give a debut to Korean striker Park Ju Young while Japanese forward Ryo Miyaichi and fellow 18-year-old Alex Oxlade-Chamberlain can also expect to make their first starts.
Wenger said: "I will be faithful to our policy but I will try to find a good mixture between youth and experience.
"You will see the likes of Ryo and Oxlade-Chamberlain. You should be excited about Oxlade-Chamberlain because he is a great talent. My target is to develop him so he confirms the expectation I have for him."