Andre Onana saved a stoppage-time penalty in Manchester United’s Champions League win over Copenhagen – Getty Images/James GillIt was a shot he would expect to save 99 times out of 100. There was not too much power on it, he was not diving full stretch, visibility was decent and the reaction as the ball squirmed past, almost as though his hands had been invisible, spoke volumes. Andre Onana dropped his face into the turf. This was a proper clanger and he knew it.Manchester United had been in control and the ascendency for 27 minutes against Bayern Munich and should have taken the lead early on before Onana gifted Leroy Sane the easiest of goals and the game turned on its head. Bayern would eventually run out 4-3 winners but the scoreline did not reflect their supremacy, even if the German champions had been far from their best.Onana probably wanted the ground to swallow him up but, in the dressing room at the Allianz Arena afterwards, United’s goalkeeper would not be found skulking in the corner, afraid to make eye contact with anyone. He had no intention of hiding. He was going to own his mistake.“He was saying to the players: ‘I’m going out there’,” said one source present. “They said he didn’t have to but his reply was: ‘No, I’m doing it’.”And so Onana got in front of the cameras and shouldered the blame for the defeat. He had, he said, “let the team down”, before going on to admit the start to his Old Trafford career had not been nearly good enough.It is more than five weeks since that blunder in Bavaria and the reality is the problems have not ended there. An error-strewn display in the next Champions League outing, a 3-2 loss at home to Galatasaray, cost his team dearly again and there was another failed, feeble attempt to keep out a shot against Brentford before a last-gasp win spared more blushes.The concerns of supporters have been understandable and United are not going to sugarcoat what has been a fairly wretched start but there is also recognition that Onana’s replacement, David de Gea, emerged defiantly from his own torrid beginnings and confidence that the Cameroon international will prevail, too.“When you look at De Gea, he didn’t have a great start,” a well-placed United source said. “We know there’s a time where these guys have got to embed and come through it. We’re pretty confident Andre has got the strength of character to deal with that. His reaction after Bayern pointed to that.”There is little doubt, though, that Onana needed a galvanising moment. Whether Tuesday night’s dramatic events at Old Trafford can prove that turning point remains to be seen but Onana’s superb penalty save to preserve a precious 1-0 victory against Copenhagen could not have felt more timely with Manchester City the visitors on Sunday.Flinging himself hard down low to his left to shut out Jordan Larsson’s penalty with the last touch of the game, Onana’s fine intervention felt significant both on a personal level and for the team as a whole and, at the very least, ensured United carried some winning momentum, however fragile, into the derby.United really will need their goalkeeper at his best against the champions and hope Onana can take some encouragement from his last brush with Pep Guardiola’s side.The Champions League final in Istanbul in June showcased Onana at his very best. He was Inter Milan’s standout performer on the night and his distribution and positioning presented huge headaches for Guardiola, who claimed afterwards that the goalkeeper had played “like a holding midfielder” and severely complicated the way his side could press in their slender 1-0 win.The ensuing months since Onana’s £47 million transfer to Old Trafford have not been as kind and, at times, it has been hard to marry that goalkeeper with the one whose kicking and handling have been so erratic for United. There has been some mitigation, of course.An injury crisis has robbed United of their first choice back four and the constant upheaval in defence has led to compromises, miscommunication and uncertainty and the structure of a timid, disjointed, passive team as a whole has been an added problem.That alone does not excuse some of Onana’s errors – as Ten Hag himself has stressed – but it has not helped a goalkeeper coming into a new league, country and culture in one of the most scrutinised positions at one of the biggest clubs in the world.Claudio Bravo, a vastly experienced goalkeeper with Barcelona and Chile, found the pressure and responsibility too much on the opposite side of the Manchester divide in 2016, with Guardiola quickly cutting his losses and bringing in Ederson. Not that it will draw any sympathy from the Catalan on Sunday.Jacob Neestrup, the Copenhagen coach, had clearly instructed players to test Onana at every available opportunity on Tuesday and it would be a surprise if City’s manager does not tell his players to do similar and prey on any vulnerabilities or insecurities.Onana, by contrast, will hope that penalty stop is the first of several positive steps forward.