It had been difficult to locate any pre-match optimism around Manchester United. The club has sunk so low, so quickly in the early weeks of the season that it was almost as if their supporters would accept a defeat without humiliation on their Champions League return. It was what they got. There were flickers from United in the opening quarter of the tie and the tonic of a first goal from the summer signing, Rasmus Højlund, to make it 2-1 at the beginning of the second-half. There were also a couple of late goals by Casemiro, which appeared to come out of nothing. But around that there were individual errors and just a glaring softness about the performance. United only seem to play in fits and starts at the moment. Their self-belief is at an awfully low ebb – it was if they, too, expected a fourth loss in five games – and the numerous injured players cannot return quickly enough. The frustration was that Bayern Munich did not have to reach their best levels to win at a canter. The image of the evening was that of the United goalkeeper, André Onana, with his face buried in the turf, burning with embarrassment after spilling a tame Leroy Sané shot into his own goal for 1-0. The inevitable Harry Kane goal celebration was not too far behind. Kane got the assist for Sané and when Christian Eriksen was penalised for handball shortly after Højlund’s goal, the England captain buried the penalty. Serge Gnabry had scored Bayern’s second and they had chances to add to their lead before Casemiro slipped and still managed to finish. Bayern know a little bit about United’s ability to come back from the dead but this is a different era, a different team. Thomas Müller, on as a substitute, would hit the post before another replacement, Mathys Tel, gave the scoreline the gloss it deserved. Implausibly, Casemiro would score again with the last action, glancing home from a Bruno Fernandes free-kick, but it never looked as though United’s away-day woes under Erik ten Hag would stop. Bayern had entered with the usual swagger and self-belief, the arena crackling with event glamour, even the club’s cheesy Euro-pop anthem adding to it. “FC Bayern, Deutscher Meister,” is one line from it and they certainly had the statistics on their side. The perennial German champions were unbeaten in their previous 27 home Champions League group phase ties and had won their opening fixture in each of the past 19 campaigns by an aggregate score of 47-2. Ten Hag was bold with his approach at the outset, Fernandes and Eriksen pushed up in central midfield, Facundo Pellistri – a pure winger – given his chance on the right, only his second start for the club. The 21-year-old Uruguayan almost enjoyed the dream start. It was United who settled the quicker and when Eriksen, having won the ball high up, saw his cross deflect, it appeared for be spinning for Pellistri in front of goal. He was thwarted by a fine Alphonso Davies challenge but the chance was still alive when the ball ran back to Eriksen. From an angle on the left, he drilled low for goal. Sven Ulreich saved smartly. United were in this as we passed the halfway point of the first-half, the travelling supporters massed up in the gods liking what they saw at that point, particularly a back-to-front passing move on 19 minutes, which ended with Marcus Rashford chopping inside from the left and firing at Ulreich. Ten Hag’s team badly needed something from their early encouragement. They did not get it and instead, Bayern stirred. Their passing had been curiously loose but now they squeezed higher and released more runners. Lisandro Martínez was required to race back to win a one-on-one tackle with Gnabry. Bayern looked dangerous up the right through Konrad Laimer and Sané. The breakthrough goal was a body blow and if Onana’s howler will take the headlines, the defending on the United left was just so soft. Sané was shown inside by Sergio Reguilón and Rashford but Eriksen did not make the tackle. Sané was allowed to swap passes with Kane and unload his shot and that was when Onana wanted the ground to swallow him up. Bayern were merciless in how they turned the screw, Jamal Musiala running up the inside left and turning into Diogo Dalot, who lost the duel. Again, it was weak. When the ball broke and Victor Lindelöf had been sucked over, Musiala pulled back for Gnabry whose finish was true. Reguilón combined with Casemiro to cross low on 34 minutes; there was nobody there for United. But it was Reguilón’s work at the other end that was the worry. He backed off before the interval and allowed Sané to curl for the far corner. It was only just wide. It was hard to ignore ten Hag’s selection crisis; he named three goalkeepers on the substitutes’ bench and only one defender – Jonny Evans, a blast from the club’s past. The present iteration had to salvage something in the second-half, even if it was only pride, and they felt their hopes surge when Højlund scored. The service to him had been minimal but now Rashford squared when he might have shot and the Dane took a touch before unloading quickly. The effort flicked off Kim Min-jae to beat Ulreich. The goal only seemed to make United more vulnerable, Musiala streaking clear to shoot almost immediately, the ball deflecting off Dalot for a corner. From it, Bayern won the penalty and it was harsh, a letter-of-the-law award, on the advice of the VAR, after Dayot Upamecano had thudded a header at Eriksen’s arm. Eriksen shrugged instinctively, maybe making the action appear worse, but there was virtually no distance between him and Upamecano. Kane did the rest and, thereafter, it was possible to fear a rout. Sané hit the post after getting in behind Reguilón, Kane worked Onana after a brilliant Musiala run and Onana also flapped at a Sané knuckle-ball. Onana would make a clutch of further saves before the late flurry of goals.