Jose Mourinho believes his Chelsea side "forgot" the reasons for their six-match winning streak in losing at Newcastle.
The Blues will this week bid to bounce back from the surprise defeat at St James' Park, which followed six wins in October, including against Wednesday's Champions League Group E opponents Schalke.
"When you win a lot, you cannot forget why you win," Mourinho said.
"You cannot think that you win just because you have a nice shirt or you are on a good run or you are in a lucky moment.
"When you think that, you are in trouble. You never can forget why you are winning matches and maybe we forgot.
"I hope now they don't forget why they won a lot of matches and why they lost against Newcastle. If they have that clear in their minds we are fine."
Mourinho made his feelings clear at half-time, when the match with Newcastle was goalless, before witnessing the Blues concede twice in the second half and suffer a first loss since consecutive defeats at Everton and at home to Basle in early September.
"At half-time I was telling them that they were competing more in training sessions than in that game," Mourinho added.
"They were just playing like the goal will arrive. When you start a game and you play 45 minutes with that dynamic - or if you prefer that non-dynamic - it's difficult to change.
"The problem for me was just the attitude. I expect my team to be much more than it was against Newcastle.
"I was frustrated because I want my team to be always active and proactive and not reactive and not waiting for things to happen.
"And I just simply didn't like (it). I want better from my team."
The defeat prompted concerns of the seemingly perennial November wobble recurring. Chelsea have played 21 games in the last three Novembers, winning just six.
The Blues boss downplayed any seasonal significance, believing the performance was a result of complacency after defeats of Manchester City and Arsenal earlier in the week.
Mourinho added: "Maybe the worst thing that happened to us in Newcastle was the easy start. They were a bit scared of us.
"You play three big matches before that. You know you have to be on the top of your level and you are the top of your concentration.
"Suddenly we get a match where we become a little bit complacent."
Mourinho had not sensed the result coming, but believes he was perhaps over-confident in his side.
"Maybe I was also influenced by the way they grew up so fast as a team and the way they so fast could play and compete the way they did in that week," he added.
"They also coped very, very well with the pressure when we put ourselves in a difficult position in the Champions League.
"After that the players reacted so well under pressure to go and to win six crucial points for us.
"Maybe I was also caught by surprise."
Chelsea play at Stamford Bridge in the Champions League for the first time since Swiss side Basle inflicted Chelsea's first home loss in the group stage of the tournament in 29 matches and nearly 10 years.
Since they won 4-0 at Steaua Bucharest and 3-0 at Schalke, with two goals from Fernando Torres, who faces a scan on Wednesday to determine the extent of his leg injury suffered in training.
Torres will miss Saturday's match with West Brom, while left-back Ryan Bertrand, who withdrew from training on Tuesday, like Torres, is also absent for the Schalke contest.
Torres' unavailability gives Samuel Eto'o, a Champions League winner with Barcelona and Mourinho's Inter Milan, and Demba Ba an opportunity.
"They work to play, they want to play, they are waiting for opportunities to play," Mourinho added.
"Hopefully they can express on the pitch the way they work during the week."