Welcome to the mad house, Ralf. If Manchester United’s incoming interim manager was not fully aware of the size of the challenge that faced him, or how erratic his new team have come to look, it was highlighted before him over the course of a helter-skelter game. Ralf Rangnick had buckled up before kick-off in the director’s box, his work permit having come through earlier in the day, although too late for him to have any involvement in the match preparations, and he could be delighted at how United found a way to win. Inevitably, it was Cristiano Ronaldo who made the difference. Back in Michael Carrick’s starting line-up, he scored twice, the second of which from the penalty spot proved to be the winner. But it only partially told the story of a United performance wracked by defensive wobbles and insecurities. Whither Arsenal. They had been presented with an early goal when Emile Smith Rowe shot past a stricken David de Gea but they found a way to throw it away. Theirs was also a display riddled with errors, together with a lack of ruthlessness, jolting their recent progress. The top three clubs in the division appear to be on another level and so we have these two, who once contested the fixture of the season, reduced to scrambling for fourth. It was easy to see the opportunity for one of them in that regard but how far they have fallen, with the past couple of months having been an ordeal for United. One pre-match statistic demanded attention. United had kicked off with five points from their previous eight games – their worst run over such a period in Premier League history. It is difficult to overstate how bad United were in the first 15 minutes. They were nervous and error strewn, offering spaces to Arsenal and, although the opening goal was coloured by strangeness, it had been signposted. Marcus Rashford had sliced inches over his own crossbar in the second minute, after a poorly defended corner and, before that, Jadon Sancho had missed an easy pass to present Pierre-Emerick Aubameyang with a shooting chance. Fred could do little right for much of the first half, miscontrolling and misdirecting, and he was central to the breakthrough goal. He lost his bearings on another Arsenal corner and trod on De Gea, causing the goalkeeper to roll his ankle and go to ground as he punched clear. Arsenal worked the ball to Smith Rowe, who shot past the prone De Gea from the edge of the area and United felt as though a whistle had to go. To them, it felt wrong. Martin Atkinson did blow but only after the ball had gone in and for what? A foul by Fred on his teammate? It was quickly apparent that the goal would stand. The weird thing was that with United there for the taking, Arsenal eased off. Ronaldo had dragged badly wide on 11 minutes when he had Rashford free to his right and, although United groped for cohesion in the first-half, they did work their way back onto the front foot. And, shortly after Gabriel Martinelli had fluffed his lines after cutting inside from the right – Smith Rowe was in space for the pull back – United found the equaliser. Remarkably, it was all about the ingenuity and vision of Fred. Ben White had erred with a clearance and, when Sancho worked the ball inside to Fred, he did well to make the angle for the cut back and execute it. Fernandes’s sure-footed side-foot was his first United goal in 16 appearances. United started the second-half with greater tempo, although they still needed De Gea to beat away a Gabriel header following a corner. Carrick’s big selection call had been to recall Ronaldo and the striker almost scored when he took a pass from Fernandes, jinked inside Thomas Partey and worked Aaron Ramsdale from a tight angle. Then he did. From an Arsenal point of view, the goal was marked by terrible defending, Nuno Tavares losing the ball to Diogo Dalot and leaving a yawning gap behind him. Dalot played an excellent reverse pass into it for Rashford and, when he crossed, White and Partey lost Ronaldo, who swept into the far corner. United exhaled in relief and promptly switched off. The space that they left on their defensive left was almost indecent and Partey was not going to miss the opportunity to exploit it, playing a pass out to Martinelli, who cut back a low cross. Martin Ødegaard arrived unchallenged and, although the finish was not completely clean, it was perfectly placed into the far corner. Atkinson had an erratic night and it was a mystery as to how he did not spot Ødegaard’s foul on Fred in real time. The Arsenal player went into the back of his opponent, getting nothing on the ball, after Fred had darted into the area but it was not long before VAR gave the referee the metaphorical tap on the shoulder. Ronaldo lashed high past Ramsdale.