* If football truly is a game of two halves, there has perhaps never been a finer example than Saturday evening’s spectacle. Manchester City dominated the first half with two goals, nine shots and a flurry of chances, but had absolutely no response in the second. Manchester United were abhorrent in the first half, failing to register a single shot, yet ended the match deserving winners. The roles were reversed at half-time, and it created an absorbing game.

The effect this could have on either side both short and long-term should not be understated. The pressure was on City to make amends with the supporters after their Champions League collapse, and a title-deciding Manchester derby provided the perfect platform. Their subsequent disintegration was startling. They will still win the title this season, but consecutive defeats to their direct rivals is quite the body blow.

For United, this was vital. The title has long been beyond them but it was crucial that they stalled the celebrations. They had to at least try and delay their noisy neighbour’s party until they had been escorted off the premises. A draw, or, better yet, a victory, would send out a statement.

It is a result and a match that has superficial bearings on this season. City can no longer win the title at the earliest opportunity, and failed to do so against their most bitter rivals. They will likely not win it by the biggest margin ever, either. But this could have a significant psychological effect going forward. United lost the battle of this season long ago, but they could yet win the war for Manchester mastery by the time Jose Mourinho and Pep Guardiola leave their respective posts.

* This was Mourinho’s most important win as United manager. The two trophies in his first season were necessary and inevitable by-products for a boss who has built his reputation on collecting as much silverware as an overactive magpie, while Europa League victory brought Champions League football after Premier League failure. It was a solid if unspectacular season.

Improvement from sixth to second would have been enough to disguise the lack of trophies, but letting a dominant City sweep them aside in their own stadium to win the title would have been incredibly damaging. United were dumbstruck in the first half, and were genuinely fortunate not to be five goals down. This was an embarrassment.

That Mourinho and United managed to salvage a victory from this game feels like a watershed moment. This was one of the biggest halves of Mourinho’s career, and certainly the biggest of his time at United. City hadn’t lost a game in which they’ve scored first all season. City hadn’t lost a Premier League game at home since 2016. Guardiola had never lost from a two-goal lead. Yet records are made to be broken.

It was a match in which everything clicked for a manager and a club that has long seemed a mismatch in style and aesthetic. Mourinho may well rank this as one of his most important victories after the 2004 Champions League final. While that feels like an exaggeration for what is essentially a dead-rubber, this salvaged a reputation that, at half-time, looked on the verge of being left in tatters.

* Just three days on from City’s Anfield humbling, the question was whether Mourinho would at least contemplate adopting similar breathless, relentess tactics that Liverpool used to such great effect earlier in the week. “You have no alternatives to beat City – you could win the lottery, hope they tackle each other and then you can stand deep in your own box and hope nothing happens but that it is not really likely,” said Jurgen Klopp after masterminding a win over City in January. Would Mourinho swallow his pride and follow suit?

“No” was his simple response on Friday when asked whether Liverpool’s midweek win over the Blues changed the complexion of this game. “Yes we have” was his reply when asked whether United had players capable of hurting City. His unwillingness to use the same tactics as Klopp when he beat the German himself recently was understandable, yet in this infernal game of ‘Rock, Paper, Scissors’, Guardiola has so often proven to be Mourinho’s Kryptonite.

The early signs suggested that United would not follow the Liverpool blueprint. City were pressured just once in possession in their own area in the first 15 minutes, when Vincent Kompany’s pass was intercepted by Ander Herrera. Nothing came of the resulting corner, and United barely put such a strain on the City defence for the rest of the first half. Considering their propensity to collapse under the slightest bit of tension, it was curious.

* The first quarter of an hour passed by with few moments of note, yet City had right to feel aggrieved as early as the sixth. David Silva’s low cross from the right-hand side was destined for Sterling before Ashley Young slipped and deflected the ball away with his hand. Martin Atkinson, as he would for much of the game, took no notice and waved play on.

It might have been the right decision by the letter of the law, but only because said law is so antiquated. The necessity for any handball to be ‘deliberate’ before it is punished is laughable, as few players outside of Uruguayan former Liverpool forwards ever actually intend to handle the ball in their own penalty area. Young had plenty of time to react to the incoming cross, and the deliberate action was in not moving his arm out of the way of the ball as opposed to moving into its path. There is little real difference, and his action denied a clear goalscoring opportunity while giving United a significant advantage. It really should have been a penalty.

* United’s refusal to blink first, coupled with City’s reluctance to take too many risks, combined to create a nervous opening period. Danilo had the only shot of the first 20 minutes, while Herrera won the only corner. These were two sides all too wary of their own vulnerabilities to try and capitalise on the weaknesses of the other.

It is no coincidence that the breakthrough came from Raheem Sterling, a player untainted by Wednesday’s collapse. The 23-year-old played like he had a point to prove, and it was he who sparked the game into life. His desire to run at the opposition betrayed the plodding passing that came before it, and it unsettled the United defence. Sterling enjoyed great success as he completed the most dribbles of any City player (3), and his first created the time and space for Leroy Sane to win a corner from which City opened the scoring. Any fears of either side settling for a goalless draw were thankfully eradicated.

* When these two sides faced in April towards the end of the 2011/12 Premier League season, the game was decided by one moment. Kompany rose highest to beat his marker from a corner and thump a header past David de Gea. Six years on, it seemed as though history would repeat itself: Chris Smalling, who failed miserably to stop Kompany on that April evening in 2012, was the culprit at the Etihad Stadium once again.

April 2012. Look who Kompany beats in the air to score the winner in a Manchester derby. pic.twitter.com/QoRHUUnVZx — Football365 (@F365) April 7, 2018

Smalling would exact his revenge in the second half, evading Kompany to volley past Ederson from a free-kick and complete United’s remarkable comeback, but that should not mask his defensive deficiencies. He is still making the same mistakes as six years ago, and United still have the same pressing need to replace him. He cannot be a regular starter for a club with such lofty ambitions.

Save for one season of excellence under Louis van Gaal, Smalling has barely developed in the six-year period between being dominated by Kompany in his own penalty area. That only Romelu Lukaku, Nemanja Matic and De Gea have played more minutes in all competitions this season is unfathomable.

* Much as they had at Anfield, the floodgates threatened to open when one goal seeped through. The only difference here was that it was City who capitalised and their opponents who capitulated.

As the unwitting culprit for Wednesday’s debacle, it was heartening to see Ilkay Gundogan prove his worth. Sterling was again the creator as he edged a pass into the German’s path, but Gundogan’s turn and instant shot was wonderful. Matic and De Gea could hardly react before City had doubled their lead.

It seemed like a statement, a reminder to Liverpool that their Champions League quarter-final tie is not over, and proof that if they score once at the Etihad on Tuesday, they are unlikely to stop there.

That said, if United can score three times against this City side in 45 minutes, one would back Liverpool to score once in 90. This was not only City’s chance to win the title, but it was an opportunity to plant a seed of doubt in Liverpool minds. They failed on both counts.

* By half-time, United were genuinely lucky not to be five goals down. Sterling missed a hat-trick of gilt-edged chances, while Gundogan cushioned a header into De Gea’s arms despite being unmarked 12 yards out. This was an all-out embarrassment, with the home fans embracing every pass with an indulgent ‘olé!’, and every tackle with a roar of appreciation.

The gulf in class was as wide as the gap between United’s central defenders, and there needed to be a response. But for that, there had to be a catalyst, a firestarter. They had managed it before – the 3-2 win over Crystal Palace last month. Yet that was a team effort with three individual scorers. This situation needed someone to take the game by the scruff of the neck and dominate against all odds. The only two times they have come from two goals down to win a Premier League game since Sir Alex Ferguson’s retirement came against Palace in March and Hull in December 2013; this was a different beast.

The first positive sign came three minutes into the second half. Romelu Lukaku won a corner which no United player chose to attack, but they would finally have their first shot moments later as Pogba curled an effort into the hands of Ederson. United had shown their first sign of life, and the Frenchman was holding the defibrillator.

* Five minutes later, United landed a telling blow. Neat build-up play from United culminated in a clever finish from Pogba, and the visitors had at least saved face after the first-half massacre.

Herrera’s assist for the goal was a delight. The Spaniard waited on the edge of the area for Alexis Sanchez’s cross, and he had the wherewithal and peace of mind to chest it past the City defenders and into the path of Pogba. It was a moment of genius from a player who has endured a difficult season.

This was Herrera at his absolute finest. No player made more tackles for either side (3), Matic (67) was the only player to have more than his 62 touches, and his substitution in stoppage-time was a befitting exit for a player who had spent the previous half hour time-wasting and winding up the opposition.

That is no criticism. It was a masterful display of game management from Herrera, who became Mourinho’s on-pitch lieutenant last season, and has been demoted to bit-part player this. Mourinho declared his midfield trio “phenomenal” after the match. Pogba and Matic are inherently more likely to receive the plaudits, but this was a return to Herrera’s sh*thousing best.

* The first half saw one City goal expose the cracks in the United defence to score another soon after. The second half was much the same, only United benefited even sooner from City’s sudden panic. Pogba ghosted in unmarked to draw the two sides level with a fine header. It hardly felt possible ten minutes prior.

The assist from Sanchez was sublime, and the Chilean was the only man to play a part in all three goals. This was the game-changing talent United were promised in January, the magician who could conjure entire colonies of rabbits from a hat even during his worst performances at Arsenal. It was as if Mourinho had threatened to take action against Atom and Humber at half-time, such was the transformation.

For a player whose earnings have been scrutinised and questioned, and who was ridiculed in some quarters for admitting last month that he was “psychologically and emotionally exhausted”, this was a turning point. The Chilean has been cast as the stereotypical individualist, but there was no better team player for either side on Saturday.

* Even before the game, the same tired, lazy points were made. “I like him, I think he’s a good player, but he doesn’t help himself,” said Gary Neville of Pogba. “If you are a wise individual, you don’t attract attention when things aren’t going your way. Pogba doesn’t work like that. Coming here with blue hair today, win it’s fine, lose and that’s going to get mentioned forevermore. It’s ridiculous.”

It is indeed “ridiculous”, but only because this somehow remains a point of contention. Pogba’s choice of hairstyle has absolutely nothing to do with his performance, nor does it have anything to do with anyone else. He dyed it while on international duty for France who, as it just so happens, play in blue.

That said, a disastrous first half hardly helped Pogba’s case. He was sloppy in possession, offered little in attack, and made no contribution in defence. He was not alone in his ineffectiveness, but a consequence of his price tag and his strange decision to live a life away from a football pitch is that he will be questioned louder and more frequently than any of his teammates.

The barrage of half-time criticism bordered on the ridiculous. Some wondered whether he was simply playing for himself and not the team, while Pep Guardiola’s pre-match revelation that City were offered the Frenchman in January heaped yet more pressure on a player constantly in the spotlight. ‘Pogba doesn’t look like an £8.9m footballer here, let alone an £89m one,’ said one journalist.

That tweet was deleted midway through the second half, Pogba essentially forcing his critics to eat their words. He scored two goals to drag United to level terms and inspired them to victory in the most emphatic way possible, finally putting an end to those who feel he has never decided the outcome of a big game.

Pogba’s next poor performance will likely be treated to the same accusations about his fashion sense, but who cares about his hairstyle when he leaves the hairs on the back of your neck standing? This was Robson; this was Ince; this was Keane; this was Pogba.

* The look on Ederson’s face when Smalling volleyed the winner was telling: it was one of exasperation, of disbelief. City had one hand and four fingers on the trophy, yet had somehow lost their grip even after the pressure had been lifted.

Ederson might be confused, but City were characterised by this sort of collapse last season. Nicolas Otamendi reverted to his error-strewn, haphazard worst, they lost control in midfield and all six of their bookings came after the hour mark as they reacted badly to things not going their way. These last three days have gone a long way to shattering the illusion of invincibility City had worked so hard to create. They are still a brilliant team, and remain one of the best in the history of the Premier League, but there are more than a few chinks in the armour.

* And so to Sterling, who was simultaneously excellent but infuriating. No player created more chances than his four, but no player spurned more chances either. David Silva put him clean through twice in the first half and he skied his shot both times, while he hit the post from six yards out in the closing stages. This was a return to the wastefulness of a player who has largely shed that tag this season.

The winger still must start against Liverpool, but City will have no chance without Kevin de Bruyne. The Belgian was rested on Saturday, left on the bench in case of the emergency that unfolded. He created one fewer chance in 19 minutes (4) than United did all game.

* It would not be a United victory without a moment of divine intervention from De Gea. Even at their best, United seem to have to rely on their goalkeeper to produce a wonderful save in every match. Fortunately for them, there are few better at producing such wonderful saves on such a consistent basis as De Gea. The Spaniard leapt to his left to claw away a Sergio Aguero header as City piled on the pressure in search of an equaliser.

“Kiss him, Ashley,” implored Neville of Young upon witnessing the instinctive stop. Any United fan would be happy to do the honours.

* Smalling’s post-match revelation that Mourinho “emphasised we don’t want to be the clowns who are sort of standing there watching them get their trophy” might have felt like a throwaway comment, but it was quite the opposite.

Speaking to Gary Neville in October 2014, Mourinho readily discussed Chelsea’s 2-0 victory over Liverpool the previous April, when the Blues derailed their bitter rivals’ title hopes. “I used the word with my players,” Mourinho began. “I said – we are going to be the clowns, they want us to be the clowns in the circus. The circus is here. Liverpool are to be champions.”

You can doubt his tactics, his methods and his approach, but Mourinho remains a master of motivation.

* The statistics suggest that Young made one foul all game. The 32-year-old is indebted to referee Atkinson, who somehow saw fit to not even book the left-back for either his first-half rugby tackle on Sterling or second-half scythe on Aguero. The Argentinean was left clutching his leg after a mistimed and misplaced slide tackle which may well have been worthy of a red card, and certainly a penalty at the very least.

Atkinson had no real control of the game from the opening minutes, overlooking clear fouls in an attempt to ‘let the game flow’. In that respect, his job is inherently difficult: if he is seen to punish a soft tackle, then he is blamed for ruining the momentum of a derby. But he set a precedent of no punishment, and bore the fruit in the second half when City’s players lost their temper at the perceived injustice. It was a masterclass in how to fan the flames of an inevitably ill-tempered match.

Martin Atkinson has completely lost control. Shambolic call for the non-penalties. — Daniel Storey (@danielstorey85) April 7, 2018

But the poor performance of the referee should take nothing away from a huge victory for United. They know they have not been good enough regularly enough this season, but this could be the start of the gap being bridged. It was a warning that although City might have enjoyed a stroll this season, United will try and match them stride for stride in 2018/19. Manchester is blue for now, but maybe not for long.

Matt Stead