Amakhosi are now without a win in their last five league games, which has certainly not pleased the Chiefs mentor, who has been critical of the players’ start to games.
"We start slow, we start arrogant. We don't start with the right dynamic, the right intention. We mention it again and again. We highlighted it.
Chiefs fell behind courtesy of an Ndumiso Mabena free-kick on 23 minutes which proved to be enough for Celtic to claim all three points.
"And then we go 1-0 down and the opponent closes the doors and we don't find the key in the final third. Simple, easy," he added.
"It's not the first. It happens again and again. And we have to ask ourselves what are we doing in the beginning," a perplexed Middendorp said.
"I already saw it in the warm-up. I had already addressed three players. The players weren't fired up enough. Experienced players - players who have to take the leadership. And then, of course, they only start taking it seriously when we are 1-0 down,” he explained.
"But as you can see the opponent closed the doors, they worked in a certain direction which made it difficult. In particular, if you don't have the key in the final third, it's not easy,” Middendorp continued.
With the season set to come to a close in the coming weeks, Chiefs are in danger of missing out on a top-eight spot. They are currently seventh on the table just a point above Celtic in eighth.
"We start again next week,” he said.
"It's not a secret. We need points. We need to do better. It's very clear," Middendorp concluded.