The Gunners remain top of the league but their title credentials look flimsier than ever after they shipped six goals against Manuel Pellegrini's free-scoring side.
That is 35 goals at home for City now this season. Hull City, back in August, was the last visitor to escape with fewer than three conceded. Whatever the club's form on the road, displays like this mean that it is unlikely any visiting team will take points from the Etihad Stadium.
City did, in truth, enjoy an cosier build-up to this fixture. Arsenal has now played three huge matches in six days and is, again, counting the cost of injuries. Manuel Pellegrini's side, by contrast, had the luxury of resting its most important players in midweek and that freshness showed.
|PLAYER RATINGS: The Brazilian midfielder excelled with a double as Arsenal were overrun|
But, for all City's strengths, it was deficiencies in the Arsenal system which helped set this tie in the Manchester club's favor.
The Gunners simply do not possess the requisite organization and competence of a side capable of winning the Premier League title. City does, whatever the league table says.
There was nothing complicated about the first goal as City converted early pressure to a tangible lead. A corner kick from Nasri was whipped via the forehead of Martin Demichelis to the back post, where Aguero finished expertly ahead of a leaden-footed Laurent Koscielny. A failure to defend set pieces adequately cost Wenger's side dearly - as it had done at Old Trafford in November.
With an equalizer that the Gunners did not merit, Arsenal surrendered parity as quickly as it was gained. Easy come, easy go. The story of the team's season to come.
Toure atoned for his error with a delightful clip of the ball to the rampant Pablo Zabaleta, who weakened Nacho Monreal throughout. His cross was met eagerly by Negredo, who showed more fight than Koscielny. The goal was a double blow for Wenger, who lost his French defender to a deep laceration on the knee in that exchange.
The key issue, however, was not Koscielny. It was Jack Wilshere, named in a left sided position, who did not show any inclination to track good runs from the fullback. The England midfielder looked frustrated throughout and his gift of possession to Nasri late in the day for Fernandinho's second goal was the low point of a sloppy display.
There was self-inflicted harm, on the third as well. A baffling decision from Ozil saw him play the ball loosely to Mathieu Flamini in an area where he did not want it. It ran away from him to Fernandinho and the Brazilian finished a supreme performance with a well-taken strike.
Mertesacker was not close enough to Silva - hardly a center forward in his own right - as Arsenal coughed up another and Wojciech Szczesny got in on the act when he brought James Milner down in injury time. Folly after folly.
City, at the moment, is limitless with regard to its potential for causing damage to fellow Premier League teams at home. The club does not need a helping hand. But this was the day that Arsenal showed weakness and vulnerability and cast doubt on the notion that it can stay the course.
Pellegrini's side may still be three points behind in the league table but it is the three-goal advantage on Saturday that will ultimately tell in the title race.