It was their heaviest defeat since they lost 8-2 a few miles across Manchester two years ago, but for Arsenal there were reasons to be cheerful. When Arsène Wenger had stopped making nonsensical claims about Everton and Southampton's parity with the Manchester City team who had just pummelled his own 6-3 – a comment beyond belief – he was jocular, smiling and by no means forlorn in the back corridors of the Etihad on Saturday.
The lift came from seeing Per Mertesacker screaming at Mesut Özil after the game, which was a sign that this is a less flaky Arsenal, equipped with strong characters. "Yes, Mertesacker is a leader," Wenger said. Özil apologised to the travelling fans for failing to acknowledge them after the final whistle.
Leaders were in evidence during the game, too – as Arsenal proved capable of coming at City, again and again to the bitter end, in a way which took us a very long way from that Old Trafford mauling which was so embarrassing that Sir Alex Ferguson later reflected he wanted it all to stop. This was the same indefatigability we witnessed in Arsenal's 1-0 Old Trafford defeat in October, when the quality of the second-half resurgence was obscured by the result.
"No," said Wenger, flatly, when it was put to him that it would be hard to pick the players up now. "Look, honestly – if we cannot pick ourselves up by being top of the league what will happen when we are not top of the league? Let's not go overboard. It's a massive disappointment… but we'll still be top."
And for once, that was not just the customary self-serving managerial propaganda. Theo Walcott, Aaron Ramsey and Mathieu Flamini performed for him on Saturday, even though it was beyond their physical capabilities to dish out some of the hammering they took in midfield. Even without any midweek exertions of Napoli to sap his energy, Jack Wilshere struggled to hold the line. (He can also expect a one-game ban for his rude gesture to City fans.) But there was certainly a champion's class about the sight of Mertesacker, diving to head a 94th-minute goal.
City's senior Spanish executives are unlikely to have been distressed to see Santi Cazorla on the bench, incidentally. They are huge admirers, considering Cazorla and David Silva to be in a league apart among La Liga players who have left for England. A good retainer of possession, Cazorla might not have displayed the Arsenal profligacy with the ball which was criminal at times on Saturday. It is even more unfathomable that Wenger did not seek to capitalise on the quality of cross Bacary Sagna can deliver. City's Martin Demichelis is a weak link. Mertesacker's goal from Sagna's cross showed up the possibilities. Nacho Monreal's selection ahead of the pacier Kieran Gibbs was also curious. Arsenal were punished by City down their left flank.
"What is important now is how we respond to that," Wenger added. There are more enviable opponents than Arsenal's next – Chelsea at the Emirates a week today – and defeats to both the Manchester teams and to Jose Mourinho's side in the Capital One Cup create an undeniable suspicion that Wenger's side do not yet believe in their ability to win in difficult places. Özil has questions to answer in that respect though he, more than any, can plead for a break. He has missed 153 of the 1,800 minutes of football Arsenal have played since his debut at Sunderland in mid-September.
The problem for Arsenal is that such micro considerations will be an irrelevance if City command Saturday's heights on a regular basis. They played with a power which shows that Ferguson wisely retreated while the going was good. Even if United possessed the extra 20 per cent his management brings, they would not hold a candle to a City squad of this strength and depth.
There are imperfections. Costel Pantilimon revealed without making any transparent clangers that he is the clubs' second-best goalkeeper. Though Joe Hart should therefore expect a Premier League recall this month, no one knows if he can improve his judgement on when to come out of his goal, decision-making vital to the kind of sweeper he needs to be for Manuel Pellegrini's City.
Sergio Aguero, who left the Etihad with a plaster cast from knee to ankle on a thigh injury, may be out for several weeks, too, though City will live. "Listen, we are going to try and break the records," said Samir Nasri, late on Saturday. With 47 goals in 16 games (an average of 2.94 each time they play) City could sweep away Chelsea's 2009-10 record of 103 in a Premier League season and even Aston Villa's 1930-31 total – 128 at an average of 3.04 a game – does not look unachievable. That's what Wenger is up against.