Three first-half goals from Ilkay Gundogan, Phil Foden and Kevin De Bruyne guided Manchetser City to an emphatic 3-1 victory over a lacklustre Chelsea side.
Callum Hudson-Odoi scored a consolation goal for Chelsea in the 91st minute.
The visitors, who were without a number of first-team players following an outbreak of coronavirus at the club, stunned Lampard's side with three goals in the space of 16 first-half minutes.
Ilkay Gundogan's crisp low finish broke the deadlock before Phil Foden doubled City's lead three minutes later, tucking a superb first-time strike beyond Edouard Mendy after fine work from Kevin de Bruyne.
The Belgian then deservedly got his name on the scoresheet with a close-range finish after Raheem Sterling's curling strike had rebounded off the woodwork.
Hudson-Odoi scored in second-half stoppage time for Chelsea, firing Kai Havertz's cross beyond Premier League debutant Zack Steffen.
The result means Chelsea have taken just four points from their last six games and City move three points ahead of them to fifth with two games in hand.