They had been left by Chelsea, the London side turning up at the Etihad Stadium last night and trampling all over Manchester City's pristine home record. A 1-0 win could still prove just a small imperfection in City's campaign, but for their manager it will look like an unseemly stain.
The Chilean has spent six months making his side's home a castle. Domestic rivals have all been held at bay. This is the first morning that City will report for training and be made to pore over a home defeat.
They had been bathing in a flood of goals at their own ground this season - in their previous four matches at the Etihad Stadium they scored 19 times - only for Jose Mourinho to pull the plug last night. This is a plumbing analogy. City might prefer it to say that their unblemished home record has just disappeared up the U-bend.
Their aspirations of recovering top spot in the Barclays Premier League from Arsenal were dented by the boot of Branislav Ivanovic, whose low, driven shot after 32 minutes was enough to take his side level with City in the table. A 1-0 win would also bear the mark of Mourinho.
It was an opportunity for him to reassert himself in the Premier League. The Chelsea manager had been irked when West Ham United had the gall to turn up at Stamford Bridge last midweek and stage a sit-in within their own half. The struggling London side had as much intention of attacking their hosts as Gandhi did when he was last invited to a dinner party.
Big Sam, the West Ham manager, would later claim that he had "out-tacticked" Mourinho. This was an assault on the English language, but also the pride of the Poruguese.
He would be purged by a significant victory, without the need for a big scoreline. Mourinho disarmed a City side which has flattened teams with heavy artillery; Alvaro Negredo, Yaya Toure, Jesus Navas, Stevan Jovetic and Edin Dzeko all taking aim last night. A late effort from the latter would end with the ball bumping apologetically against an advertising hoarding.
It was a meek sight and one which City supporters are not accustomed to bemoaning. Sergio Aguero was out injured but there were still good chances for Yaya Toure and David Silva. Neither wound up in the net.
"They've been phenomenal scoring goals and turning teams over," said John Terry, the Chelsea defender. "It was important not just for us but for other teams, showing that they can be beaten."
And that they can be bruised. The London side went ahead after an initial shot by Ramires was blocked, only for the ball to break for Ivanovic to thump a low shot into the net.
It was a goal celebrated by the travelling support but also in London, where Arsenal have now stolen a march on City. They might as well have traipsed muddy footprints through Pellegrini's front room.