Chelsea was handed its heaviest loss in 28 years on Sunday when Manchester City routed Maurizio Sarri's side 6-0 in the Premier League.
The meeting of the last two champions was a complete mismatch as Sergio Aguero scored a hat trick for the second successive weekend.
City regained top spot from Liverpool in its title defense as 2017 champion Chelsea ended the weekend by dropping out of the Champions League places into sixth.
Raheem Sterling scored twice — City's opener in the fourth minute and the sixth in the 80th — and Ilkay Gundogan also netted.
It was Chelsea's third consecutive away loss in the league, following a 2-0 collapse at Arsenal and 4-0 humiliation against Bournemouth.
Chelsea's previous heaviest loss came in April 1991 — a year before the inception of the Premier League — when Nottingham Forest beat the west London club 7-0.