As Kevin De Bruyne ambled around the touchline to the dugout after his 87th-minute substitution, a bottle flew towards him from the Clock End.
The Belgian waited until the last second to duck, just enough for the missile to sail centimetres over his head, and refused to quicken his pace, even as another landed at his feet.
This was, after all, a night when the champions demonstrated their nerve and kept their cool, while Arsenal missed their target and surrendered top spot in the Premier League.
City's 3-1 win felt potentially seismic in the title race, moving them ahead of Arsenal on goal difference, albeit having played a game more, and perhaps kick-starting an ominous run from Pep Guardiola's side.
Mikel Arteta claimed that his side had "given" the game to City, but while his frustration was justified, this was only partly true. Certainly, Arsenal were the makers of their own downfall, with individual errors in the build-up to all three of City's goals.
Takehiro Tomiyasu, picked ahead of Ben White at right-back, under-hit a back-pass to Aaron Ramsdale which De Bruyne intercepted before finishing magnificently over the goalkeeper, and Gabriel and substitute Leandro Trossard lost possession before smart finishes by Jack Grealish and Erling Haaland in the second half.
There were shades of the old Arsenal in the way individual errors undermined an otherwise encouraging performance, while Arteta lamented their wasteful finishing, with Eddie Nketiah twice heading wide from good positions.
"If you give [away] three goals the way we did and don't put away the big chances that we had the margin for error is almost zero," said Arteta. "It's a shame, because we really had them. We just move on and realise why we lost the game. I think we lost it."
City, though, force these mistakes from opponents, and they played with the aura of champions in a ferocious atmosphere in north London, exuding a composure and menace which Arsenal struggled to match after Bukayo Saka equalised from the penalty spot before half-time.
There was also an element of apprentice being outfoxed by master again, as Guardiola got the better of Arteta with two astute tactical decisions on the night.
From the off, City were unabashedly route one, bypassing Arsenal ferocious midfield press with a direct approach, spearheaded by the magnificent Haaland. Even as Arsenal controlled the opening 45 minutes, Haaland was a constant handful for Gabriel and William Saliba, causing jitters in Arteta's back-line whenever the ball entered his orbit.
City's opening goal, against the run of play, came after the Norwegian flicked on Ederson's punt and De Bruyne raced onto Tomiyasu's error.
"I don't know if it's experience or bad luck," said Arteta. "I've never seen Tomiyasu make that pass in seven years and he did it today. They have the quality to punish you."
City's directness felt a far cry from Guardiola deploying Grealish or Phil Foden — an unused substitute again — as a false nine, and suggested the Catalan is not above learning from Sean Dyche and Thomas Frank.
Dyche's Everton and Frank's Brentford both caused Arsenal problems with a physical centre-forward in Dominic Calvert-Lewin and Ivan Toney, respectively, as Arteta's side were beaten at Goodison Park and drew with the Bees last weekend, part of a run of four games without a win, bookended by defeats to City.
Concerningly for Arteta, if City are prepared to mimic the approach, everyone will, and there is now a blueprint for unsettling his side which will not have gone unnoticed by the Spaniard's predecessor Unai Emery, whose Aston Villa side lie in wait for Arsenal on Saturday.
Guardiola also made a canny tactical tweak in the second half, replacing Riyad Mahrez with Manuel Akanji and moving Bernardo Silva from left-back to the right wing. It strengthened City's defence and gave them another weapon going forward. The warning signs were there when Gabriel hauled down Haaland for a penalty, only for the VAR to rule the striker offside.
No matter, Grealish soon finished a fine move from Haaland's pass following a smart dummy by Ilkay Gundogan, and City's centre-forward then continued his procession to the Golden Boot with his 26th goal of the season.
The psychological blow of losing top spot could be significant for Arsenal, although Arteta urged his players to take the positives after a performance in which they matched City for long periods but came up short when it counted. "We have to move on, because the performance was there in many situations," said Arteta. "For our team to play at the level we have to play to reach that is very difficult."
