Glenn Loovens admits Celtic must raise their game if they are to successfully defend their SPL title.
The Hoops have claimed the crown in each of the last three seasons and had appeared to be well on course to replicate that achievement this term.
However, a run of just one win in six games has seen them surrender top spot in the table to Old Firm rivals Rangers - albeit on goal difference.
A 1-1 draw at Motherwell on Sunday inflicted the latest blow on their title aspirations, with missed chances yet again costing the Glasgow club dear.
Loovens admits he was at fault for the hosts' late leveller at Fir Park, but believes the contest should have been settled long before Paul Quinn cancelled out Scott McDonald's opener.
He said: "If you saw the game, we had plenty of chances to kill it off and they had one shot at goal and it went in.
"I'm disappointed, the free-kick was a stupid one to give away.
"But I just had to deal with it. It was just a free-kick and we weren't quite organised because they took it quickly to the side. We weren't ready for it.
"That's a thing we can have a look at but, apart from that, we clearly dominated the game.
"Of course we are concerned. We know we have dropped a lot of points.
"We are still well in the race for the title but we have to improve.
"We created many chances, so I am sure we will turn things around next time.
"But we have to make sure we go on a great run again and we have to start taking our chances."