Antonio Conte felt Chelsea failed to pay the attention required to play like a great team in their 2-1 loss to Liverpool at Stamford Bridge on Friday.
Chelsea took on a passive role in the first half and their defence was caught short when a quick free-kick by Philippe Coutinho was volleyed home by Dejan Lovren after 17 minutes.
Jordan Henderson added a sensational second before half-time with a looping 25-yard effort that Blues goalkeeper Thibaut Courtois had no chance of stopping, but Diego Costa halved the deficit just after the hour-mark.
Chelsea had to come from behind to draw 2-2 with Swansea City last time out, and Conte, who suffered his first defeat since taking over the club, admitted his team are too often guilty of complacency.
"To find a reason [for defeat] sometimes is easy, sometimes hard. The goals we concede are strange. We must feel the danger and today we didn't," he told Sky Sports.
"We have to reflect a lot on this game because it is important to understand the situation if we don't want to repeat another bad season like last season. We don't feel the danger, never.
"In the second half, the approach was better, and we scored the goal - another through Costa - but in the end it's a pity.
"We played without intensity and you must pay attention to details if you want to play like a great team. Chelsea are a great team but we sometimes don't pay enough attention.
"With Liverpool when you concede space it's very difficult - they have three fast strikers all with good technique.
"At this level it's important to pay attention to the details."