City were brought crashing back down to earth with a second-half defensive horror show against Cardiff.
The hosts recovered from going a goal down after the break to score three times - two coming from corners - as the Blues had their wings clipped by the Bluebirds.
Edin Dzeko's stunning goal after 52 minutes ultimately counted for nothing as Aron Gunnarrson and Frazier Campbell (2) exposed some slack marking by Manuel Pellegrini's men who will surely spend the majority of next week working on defending set-pieces.
Alvaro Negredo pulled a consolation goal back in added time, but the damage had already been done. What a difference a week makes.
This was Cardiff’s first top-flight home game for 51 years, so there was a sense of occasion before the game.
The home fans, knowledgeable enough to know they need to make the Cardiff City Stadium a fortress if they are to survive this season, were as partisan as you’d expect and this won’t be an easy place to come for any team
Not that the Blues traditionally enjoy trips to South Wales where it was 60 years since the last City goals were scored on Welsh soil at this level. With successive blanks away to Swansea in the last two years, it is a worrying trend for a team with title aspirations.
Vincent Kompany and Matija Nastasic were absent from the starting line-up as Pellegrini gave Javi Garcia the opportunity to impress at centre-half alongside Joleon Lescott. Yaya Toure, making his 100th Premier League start for City, was handed the captain’s armband.
Anyone hoping that the Blues were going to start this game where they’d left off against Newcastle would have been disappointed as the hosts began at a high-octane level, pressing high up the pitch and generally surfing a wave of adrenaline.
City refused to appear to ruffled as they dealt with most of the early threats in a calm and controlled manner in a half of few clear cut chances.
In fact, the Blues waited 22 minutes before creating a meaningful opportunity as David Silva and Sergio Aguero combined to create confusion in the six yard box before the home defence cleared their lines.
The Bluebirds packed their defence and midfield every time City threatened, but it was only in the latter stages of the opening period that the home team began to look dangerous with Frazier Campbell latching on to Garcia’s backwards header but Joe Hart raced off his line to make an excellent save.
On a hot day in the Welsh capital, the question was could Cardiff maintain the tempo they’d set in the first-half? The answer would become clearer later in the game but the axis swung the visitors' way seven minutes after the break as City opened the scoring with a beauty from Dzeko.
It came out of nothing, too, as Toure played the ball to Aguero whose delicate lay-off was collected by Dzeko. He took one look up before unleashing a superb 25-yarder past Marshall into the top corner
It was further evidence of why Pellegrini rates the Bosnian so highly and it should have been the platform for the Blues to take the game by the scruff of the neck and go on and win – but within seven minutes, Cardiff were on level terms as Kim skipped past Gael Clichy to find Campbell who was denied at point-blank range by Hart - but Aron Gunnarsson reacted quickest to poke the ball home and send the Welsh fans wild.
It was a soft goal to concede and not particularly well defended, either. It was also the perfect fillip for the Premier League new boys who could easily have wilted after going behind but instead now had the wind in their sails.
There was worse to come as Campbell was allowed a free header from a corner to put the Bluebirds 2-1 up on 79 minutes.
If Pellegrini was left scratching his head as to how his side now found themselves behind after being in front and dominating possession, he wasn't alone. With the Blues looking rattled and unable to recover, Campbell struck again with a headed goal from another corner to end the game as a contest on 88 minutes.
Conceding one goal from a set-piece was worrying; two was careless.
Negredo pulled one back in added time, nodding home Silva's cross, but the damage had been done as football proved yet again that you really are only as good as your last result.
The Blues' boss will expect a reaction against Hull next Saturday as, no doubt, will the players themselves.