The Amakhosi boss also explained what he told his players during the week after beating Orlando Pirates last weekend.
Moreover, the German manager lambasted Usuthu’s defensive approach who sat back hoping to catch the log leaders on the counter-attack.
“From the beginning, was just too casual. We spoke about it during the week. I was hoping everybody understood the message,” Middendorp told SuperSport TV.
“Winning the derby, it is always something after this, you get relaxed, too relaxed, you putting yourself into it and you have a fantastic chance to make it 1-0.
“Too casual again, it just gets kicked in I’m talking about this excitement to make a hundred percent sure.
“Ok, in the critical phase you get the 0-1 and now get to play against the wall and block of defensive, quite deep, you don’t get quite an open door and then you lose again.”
The only goal of the match came through Bonginkosi Ntuli ahead of the interval as Middendorp rued their failure to convert.
“This is all that I’m talking about. It’s definitely when you find the right identity with the game when you in and really in,” he added.
‘I’m not taking it casually then something like this happens and then all of a sudden getting yourself into a shocking situation, 0-1 three-four minutes before halftime so then all of a sudden you have to correct yourself as an individual.
“As a collective and then it’s difficult you play into the cards-defensive work from the opponent’s side and then it’s a war as we have seen.
“We had enough strikers on the field to make it happen [equalize], but good it didn’t work. We have to ask ourselves what we have done today.”
Meanwhile, Middendorp will challenge his troops to bounce back against Bidvest Wits next week as they look to reach the 50 points mark at the summit.