Derby County scored two first-half goals at Stamford Bridge but poor defending haunted them during a narrow EFL Cup defeat to Chelsea.
Chelsea overcame a Halloween fright on Frank Lampard's return as two own goals cost Derby County in a 3-2 loss in the EFL Cup on Wednesday.
Impressive in beating Manchester United in the third round, Lampard's young side were the architects of their own downfall in London as Chelsea loanee Fikayo Tomori and Richard Keogh both put through their own net inside 21 minutes.
The hosts were not immune to horror moments at the back, with Jack Marriott and Martyn Waghorn on target in a thrilling five-goal first half that concluded with Cesc Fabregas restoring his team's lead.