If anyone were in any doubt how important the Manchester derby was to fans of City they need only to study the looks on the faces in the Etihad Stadium after each United goal. Alternatively a quick search on YouTube reveals a host of in-the-ground fan cams and on social media stills of Sky Sports images of crying supporters post-match give the impression of a feeling of desolation. The chance to win the title at Old Trafford is something that Sir Alex Ferguson experienced relatively infrequently given his immense success and the chance to do so against the likes of City or Liverpool never arose. To triumph in such circumstances would be the ultimate celebration/schadenfreude crossover and it was within Guardiola’s side’s grasp. Even more so when 2-0 up at half time having given Mourinho’s team, who did not record a single shot in the first period for the first time since 2015, an absolute pasting. The blue majority were understandably giddy. And then, in a compelling second half which reminded us why the game is so enthralling, Paul Pogba and United threw off their tentative conservatism and turned the game on its head. Football, bloody hell.

City, of course, will still win the Premier League, a success which they thoroughly deserve. It may not be next week when they travel to a buoyant Tottenham, however, for they currently resemble a wounded beast, dazed and confused by a surprise attack when they thought they were untouchable. Perhaps, as much as the defeat, the opponent and the manner of it on Sunday was painful, it is also the knowledge that their team are more vulnerable than they imagined that has dampened the mood. First Liverpool – twice – and now United have exposed a soft underbelly, an Achilles Heel barely tested by opponents who have faced Guardiola’s artisans all season and played dead. Only a few weeks ago Chelsea travelled to The Etihad Stadium, played Eden Hazard as centre forward and barely attempted to cross the half way line, challenging for the ball only in their own defensive third. City are just too good offensively to hope that you can set your team up in a compact defensive unit and prevent them from creating chances.

United found that out in a chastening first half on Sunday, two goals down when it should have been six. And yet, in what has become a rarity for Jose Mourinho, he sent his team out after half time and let the shackles off the likes of Alexis Sanchez, Paul Pogba and even Ander Herrera. Sanchez drove at the heart of the City defence. Paul Pogba, who had taken ridiculous stick – including from Gary Neville – in the run up to the game for having blue hair, was released and drove into the home side’s penalty area at every opportunity. The result was two goals for the Frenchman, the first set up by a stupendous Herrera chest assist as United flooded the box. And then came the coup de grace, Sanchez flighting a free kick to Chris Smalling – at fault for Kompany’s header from a corner but left totally unmarked here – to side-foot home the winner. Bedlam, and despair. Under sustained pressure City had crumbled, and a sensational De Gea save from Aguero confirmed the victory.

One wonders, therefore, whether this last week has changed the narrative around City, from pundits and fans to future opponents this season and, more importantly, next. Perhaps City’s start to the season and the genius of Guardiola blinded us all, creating the conditions in which the Premier League became a procession. They can be got at, the evidence is clear, but only if you are brave.

Which brings us on to Jose Mourinho, the arch pragmatist, who so often in his time at United has fallen back into conservatism when the pressure is on. In the reverse fixture at Old Trafford in December he set his team up largely to contain, an opportunity perhaps lost given that on the rare occasions that they asserted pressure in City’s final third the visitors looked vulnerable. In the Champions League against Sevilla he again preferred caution, with terminal consequences. Those who have defended his approach argue that his back line is not good enough to allow for offensive endeavour, but over at Anfield Jurgen Klopp has created an attacking unit that now has one foot in the semi-finals of that competition and that has demolished Guardiola’s team twice in a few weeks with a distinctly average defence and midfield. In the face of that retort, some argue that United do not have the offensive weapons to make that work, but in Pogba, Lukaku, Sanchez, Martial and Rashford Mourinho has plenty of talent at his disposal to do damage to any team, domestically at least. Paul Pogba told Thierry Henry post-match that he is not allowed to drive forward when playing in a midfield two and even in a three he needs the freedom to do so.

But credit to Mourinho for changing his team’s mentality at half time, for allowing his creative players in Sanchez, Pogba and Lingard – even Herrera – to drive forward and play twenty yards further up the field. Critics might say that at 2-0 down there was little point in United continuing as they were, but the temptation must have been there to tighten up, take a loss and get the hell out of Dodge. Further credit to the Portuguese for not allowing his team to fall into their annoying habit of dropping deeper and deeper towards their own goal when defending a positive position. Perhaps, therefore, Sunday will have provided him with a ‘Eureka!’ moment, giving him the faith in his attacking players to make their positivity count. The biggest beneficiaries by far were Pogba and Sanchez, but Anthony Martial and Marcus Rashford can only improve if given greater on-pitch freedom when they get their chances.

United’s comeback win over City will live long in the memory for Reds, as a humiliating bloody nose was turned into a footballing orgasm. Fans of the home side were understandably devastated that their once in a lifetime chance to win the title by beating their city rivals was blown in dramatic fashion. Whilst Guardiola’s side will still deservedly have their day in the sun at some point in the next few weeks – and the kitted-up children of the players will finally get to do a lap of honour at The Etihad – one wonders if the significance of Sunday’s traumatic defeat may extend beyond the immediate aftermath. For the other nineteen Premier League managers it proved once again that this City team is poor defensively and can crumble under pressure if they are attacked. It has been a chastening week for the Sky Blues and their manager and the supporters have suddenly seen a weakness exposed that they did not know was there. Remarkably this is the first time this team has faced genuine adversity this season and it has not responded well.

There must also be some hope that Jose Mourinho watches Sunday’s match again and observes and recognises the difference in his best players’ performances when let off the leash. With a Champions League place secured and a soft run-in to the Premier League season there must surely be a temptation to attempt to play with some freedom for the remainder of the campaign. The FA Cup semi-final against Tottenham is likely to be another painful experience if United approach it as the underdog. Perhaps Sunday demonstrated to the Portuguese that with the attacking quality he has fortune might well favour the brave.