Chelsea manager Thomas Tuchel has said he made a mistake by allowing Romelu Lukaku to play during the Blues' 3-2 loss away to West Ham on Saturday.
The Blues lost for the fifth time in the league under Thomas Tuchel and eventually slipped to third following Manchester City and Liverpool's wins against Watford and Wolves respectively.
Lukaku was a second-half introduction, replacing the injured Kai Havertz at the London Stadium.
The Belgian, who is only returning from injury, had little impact as the Hammers scored two second-half goals to come from two goals down to win.
Speaking after the match, Tuchel acknowledged it was his fault as Lukaku still lacks match fitness.
"It’s my fault," he said. "I don’t think he is ready for 45 minutes physically but still we decided to bring him on for his height because we lost Kai.
"Kai had a crucial role in defending set-pieces, which is a huge threat from West Ham, so this is on me. I took the decision so it’s my responsibility,"
He added that no one should have doubts over the bigger picture and that the small mistakes that have cost them points in the last two games will be handled.
"It’s details and you can always solve the details," he added. "There is no need to question the big picture and no need for major doubts.
"In my opinion, it’s obvious why we did not have the result that we wanted against Man United and West Ham so it’s about details. That’s why I think we can sort it out straight away.
"Nobody wants to make mistakes but it won’t help if we just say “hey, don’t make mistakes anymore.” We have to go through it and we need to be better in decision-making in crucial moments of matches to be able to have clean sheets or concede a maximum of one,"
Chelsea turn their attention to Champions League action with a trip to Russia to face Zenit St. Petersburg on Wednesday night.