Manchester United 4 Manchester City 2

These are the moments when it is starting to feel like English football might be getting the old Manchester United back. They have taken their time and there are still imperfections but, finally, they are operating with the dynamism and sense of adventure that is supposed to be mandatory for any set of players who pull on their colours.

Louis van Gaal’s team showed enough superiority here that by the end it was impossible not to think Manuel Pellegrini’s position at Manchester City had been weakened to the point where the damage might be irretrievable.

This was City's sixth defeat in eight matches and their worst run under Pellegrini now stretches to four victories in 15 games. Nobody said it would be easy getting to the top of their sport and staying there but their owners are entitled to expect better, approaching seven years since the money started pouring in from Abu Dhabi, than being thrashed by the team they had made a habit of beating.

The potential ramifications for Pellegrini are obvious and United were ruthless in exposing his team's flaws once they had shaken off the early setback of Sergio Agüero giving City a seventh-minute lead. Ángel Di María and Radamel Falcao, the two players who were supposed to spearhead Van Gaal's first season in charge, did not even get on to the pitch until the score was 4-1. Yet Van Gaal always did say that the structure of the team was more important than grade-A players. Now we are seeing the hard evidence. The plodding football we saw earlier in the season is starting to feel like a trick of the imagination.

Who could have thought, for example, that Ashley Young would hold this kind of influence when the superstars started arriving last summer? Young was once in danger of being the player the Old Trafford crowd disliked the most. He is now playing with enough distinction that the watching England manager, Roy Hodgson, must be considering a recall. Young started United's recovery here with the equalising goal and his new confidence could be measured in that moment before helping Marouane Fellaini to make it 2-1 when he bamboozled Pablo Zabaleta with a back-heeled nutmeg.

Juan Mata was superb again, particularly when it came to his triangular passing on the right with Ander Herrera and Antonio Valencia. Wayne Rooney was indefatigable in attack and Fellaini was hugely effective. They also showed great competitive courage bearing in mind the way City set off like a team in a hurry.

Jesús Navas really ought to have scored inside the first five minutes after racing clear on to Martín Demichelis’s ball. David de Gea was quickly off his goalline to block with his feet but United looked jumpy and Agüero’s goal was a collective failure on their part. The move began with Gaël Clichy, advancing from his left-back position, drifting between a couple of half-hearted challenges. James Milner’s clever pass played Silva inside and, again, the defending was far too generous. Silva simply put his foot on the ball, waited for Agüero to dart forward and picked out his team-mate like a force of habit. It was Agüero’s first goal since 24 February.

The problem for City was the game did not stop there. Zabaleta was also partly to blame for the second goal and Demichelis will not want to see replays of Mata making it 3-1 or Chris Smalling heading in United's fourth. David Silva was a constant menace and Agüero showed his threat again late on when he turned in Zabaleta's cross to complete the scoring but City have regressed badly from that point on New Year's Day when they were joint top with Chelsea. There was also more evidence of Vincent Kompany's recurring injury issues. Kompany did not last beyond half-time because of his hamstring troubles.

The game started lurching in United’s favour after 14 minutes when De Gea aimed a long clearance over to the left where Fellaini and Herrera had doubled up on Zabaleta. City were vulnerable as soon as Zabaleta lost his balance. Young had gambled with a run to the near post and, though Demichelis had followed his run and was first to the cross, the ball was not cleared, spinning upwards and coming down for United’s left-winger to hook an improvised shot into the exposed net.

City, and Silva in particular, continued to move the ball at a speed that frequently troubled their opponents but they also had a raw edge. After 27 minutes, Young subjected Zabaleta to the reverse nutmeg then took the ball back from Daley Blind. Fellaini had made his way around to the far post and had several inches on Clichy, with a run to get even more leverage and score with his header.

City had legitimate complaints that Fellaini was fractionally offside, even if it was by merely a tuft of that hairdo, and more grievances about Mata's starting position when Rooney played him in for his goal midway through the second half. Yet Pellegrini's complaints should start with his team's defending. Demichelis had lost the ball to Fellaini for Mata's goal and did not follow Smalling's run when the defender headed in Young's cross to beat Joe Hart again. United were rampant at that stage and Agüero's second goal came almost in slow motion, with barely a flicker of celebration.

(Guardian service)