Chelsea’s miserable recent run continued with a crushing home defeat.
They were three down by half-time at Stamford Bridge after goals from Ilkay Gundogan, Phil Foden and Kevin De Bruyne.
Substitute Callum Hudson-Odoi netted a stoppage-time consolation, sliding in at the far post to tuck away Mason Mount’s low cross from the left.
Two goals in less than three minutes midway through the first half put Manchester City in control.
Gundogan scored a superb opener, turning away from Thiago Silva near the edge of the penalty area and thumping a right-footed shot into the bottom corner of the net.
Foden added the second by slotting home after being teed up by De Bruyne after they had linked up nicely down the left-hand channel.
And worse followed for the hosts when former Chelsea man De Bruyne added the third following a counter-attack shortly before half-time.
Raheem Sterling sprinted towards goal after N’Golo Kante’s error and, after going past keeper Edouard Mendy and being crowded out, the England star fired against the post.
The rebound dropped to De Bruyne, who coolly applied the finish.
Frank Lampard’s side have now lost four of their past six matches.
Lampard opted to deploy Timo Werner in his preferred central position and left strikers Tammy Abraham and Olivier Giroud on the bench.
The intention was for Werner to exploit potential space in behind the City defence.
However, it was another frustrating outing for the German, who has now gone 12 games without a goal.
Chelsea: Mendy, Azpilicueta, Zouma, Silva, Chilwell, Kante (Gilmour 64), Kovacic (Havertz 77), Mount, Pulisic, Ziyech (Hudson-Odoi 64), Werner.
Subs not used: Kepa, Rudiger, Jorginho, Abraham, Giroud, Emerson.