The Gunners were by no means embarrassed by Pep Guardiola‘s side – as they have been all too frequently against fellow top-six clubs in recent times – but City carved Arsène Wenger's side open with ease all afternoon to move eight points clear of rivals Manchester United in second ahead of the day's late game.
Kevin De Bruyne put City ahead after 19 minutes, finding just enough room to get a left-footed shot off from the edge of the penalty area, steering the ball into the bottom left-hand corner with unerring accuracy.
And just five minutes into the second half Sergio Agüero doubled up. Raheem Sterling got in behind and was felled inside the box by Nacho Monreal to hand the hosts a penalty which the Argentine converted.
But the Gunners got one back a matter of minutes after Alexandre Lacazette was brought off the bench. The French forward collected Aaron Ramsey's pass and shot through Ederson's legs to reduce the arrears.
And with 15 minutes to go City made the points safe, benefitting from some generous Arsenal defending. The Gunners switched off completely allowing David Silva to pull across the box for Gabriel Jesus to lash home.
Arsenal struggle on the flanks
In the first half, in particular, the Gunners looked vulnerable down the flanks. Manchester City clearly targeted the wide areas when it became apparent Arsenal had set up with a back three and not a back four as originally expected.
Sterling and Leroy Sané were a threat throughout for City, getting wide and stretching the pitch to give Arsenal's back three a dilemma.
And it worked to a tee. Time and time again Sané made problems for Laurent Koscielny, pulling him out of position and going one-v-one. Fine defender though the Frenchman is, he is not the most mobile and relies on his reading of the game, rather than his physical assets.
But he was pulled from pillar to post by Sané down the left – particularly when Héctor Bellerín was caught bombing forward and left space in behind. When wide, City got balls into the visitors' penalty area. Only City's profligacy in front of goal prevented them building up a handsome half-time lead.
That changed early in the second half when Sterling got in behind Monreal and Sead Kolašinac, forcing the former to bundle him to the ground an earn a penalty which Agüero converted.
Delph shows why he isn't a full-back
The England international was frequently caught drifting inside to a more natural central midfield role. And while that might have been a Guardiola ploy designed to overload Arsenal's two-man central midfield pairing of Granit Xhaka and Ramsey, it left the left flank open on numerous occasions.
If Arsenal were going to score it seemed a safe bet the goal would come from down Delph's side with Bellerín afforded lots of room to manoeuvre.
Conversely, on City's right-hand side, the Gunners were unable to really get Sead Kolašinac in the game as Kyle Walker – while still committing a large proportion of his time to getting forward – did not extend the same generosity to the Bosnian wing-back.
Wenger's tactical gamble fails to pay off
Prior to the game much of the talk was about the Gunners reverting to a back four for the first time since the humbling 3-0 loss at Crystal Palace in April. That night proved seminal for Wenger who has stuck with a back three ever since, winning the FA Cup at City's expense along the way.
And the inclusion of Francis Coquelin, making his first Premier League start of the season, suggested a return to a back four. However, the French midfielder was surprisingly installed at the heart of the Gunners' back three, flanked by Koscielny and Monreal.
That, perhaps, shouldn't have been such a surprise given Wenger has used Mohamed Elneny at centre-half in the Europa League, such is his commitment to utilising wing-backs nowadays.
But the gamble failed to pay off which City thriving in the wide areas throughout. And Wenger conceded defeat ten minutes into the second half by withdrawing Coquelin in favour of a proper centre-forward in Lacazette.
And Wenger's decision was vindicated minutes after the change as the former Lyon striker halved the deficit.
KDB the man for the big occasion
The Belgian maestro was rightly named man of the match at the Etihad Stadium having run the show from midfield and scored the opener with a smartly-taken strike from the edge of the penalty area when there appeared to be little on.
De Bruyne's influence was felt in more than just his goal, though. The former Chelsea man was at the centre of everything good for the Citizens, drifting between the lines and pulling players out of position.
He led the way for dribbles completed with five. But there was another, less expected, fact to his game. With five tackles won, the 26-year-old was only just behind team-mate Fernandinho (six) in that metric and second best on the field for winning the ball back.
This was his second big contribution against a top-six rival this season, having bagged the winner against Chelsea at Stamford Bridge, and you wouldn't bet against it being his last.