Chelsea crashed to a sobering defeat at the Eithad this afternoon, putting this title defence under serious scrutiny.
Goals from Sergio Aguero, Vincent Kompany and Fernandinho means that the champions have just one point from their opening two Premier League matches.
The Blues were anaemic in attack they will need to get the ball to Diego Costa more and earlier.
Despite having periods of pressure and possession, Chelsea miserably failed to trouble City goalkeeper Joe Hart, bar on Eden Hazard effort.
By contrast, City showed off their heavyweight attack and raped the benefit.
But home superiority eventually broke the Chelsea resistance, on 32 minutes, and it was Aguero who cooly slotted home a left footer from eight yards that gave Begovic no chance,
Diego Costa went down in a heap, from a robust Vincent Kompany offering the chance for treatment. But banned Eva Carnerio and physio Jon Ferms were not in evidence and their replacements, Doctor Christopher Hughes and physiotherapist Steve Hughes remained firmly in their dugout.
With Jose Mourimho prowling his dugout, it was deemed that Costa did not need treatment.
The Blues recovered their composure as the half developed and while getting into City's final third was mo problem, producing an effort on goal eluded them.
The medical pair entered the fray two minutes before half-time to treat Cary Cahill whose injured his nose in a clash with Begovic.
Chants of "Eva" rang round the Etihad as they treated the defender.
They continued to treat him on the sidelines and failed to see, seconds later, Diego Costa crumble to the ground clutching his head. It was left to City's doctor to come in the field to treat the Chelsea hit man.
Playing with nine-man City launched an attack which ultimately came to nothing but a chorus of "You don't know what you're doing." was soon in evidence around the ground.
Mourinho replaced skipper John Terry at half-time for Kurt Zouma, presumably as result of the inability of Terry to shackle Aguero.
With Branislav Ivanovic booked for fouling Raheem Sterling with seconds of the restart the omens were not good for Chelsea. However a strong period of position saw the league champions tuck the ball home through Ramires only to see his effort ruled out for offside.
That was the Brazilian's last contribution and he was replaced by Juan Cuadrado on 64 minutes.
Eden Hazard, on another day would have stroked home the equaliser in 70 minutes, but after excellent set-up play by Costa, the Belgium midfielder snatched at his drive, allowing Joe Hart to stick his legs out to smother the effort.
Mourinho's last throw of the die was to bring in Radamel Falcao as they were defending a corner on 80 minutes. Willian went off, but from the resultant cross, Kompany got above Ivanovic and glanced the ball past Begovic to double the lead.
Terrible defending two minutes later, Ivanovic the main culprit, allowed Fernandinho to thunder a rasper low and hard past Begovic to seal the three points for the home side.
Teams: Chelsea, Begovic, Ivanovic, Fabregas, Ramires, Hazard, Costa, Matic, Willian, Cahill, Terry, Azpilivueta
Subs, Blackman, Zouma, Falcao, Cuardrado, Mikel, Remy, Loftus-Cheek
Man City: Hart, Sagna, Kolarov, Mangala, Kompany, Sterling, Silva, Toure, Fermandinho, Navas, Aguero
Subs, Caballerom Demichelis, Zabaleta, Clichy, Nasri, Iheancho, Bony
Referee: Martin Atkinson
Ends