Welcome to hell: Manchester United’s notorious introduction to Galatasaray from 1993 has a new twist. Back then, it was an away goals defeat in Istanbul that saw United knocked out of the Champions League, their players knocked about by the local constabulary during a post-match fight in the tunnel. Here, it was a continuation of the agonies of the season, Erik ten Hag’s players doing plenty to raise the hopes of their fans. In particular Rasmus Højlund, who twice put United in front, his second a beautiful mix of pace from the halfway line and composure in front of goal. How United burned down their platforms. They reinforced the notion that they are never more vulnerable these days than when they are ahead and they did so with a masterclass in how not to defend, the fragility of their collective confidence – from the goalkeeper, André Onana, out through a less than first-choice back four and into defensive midfield – laid bare. After the 4-3 defeat at Bayern Munich in the opening set of Champions League group-phase ties, their chances of advancing to the last 16 have been left to hang by a thread. More alarming is what this performance says about where the team is heading under Ten Hag. United have made their worst start to a top-flight season since 1989, “ta- ra Fergie” and all that, losing four of seven games. Now this, defeat in a must-win Champions League tie, that it looked as if they were going to win. When Højlund made it 2-1, they were in complete control. Which only made the complete capitulation thereafter more shocking. Not that the natives in these parts are immune to shock. It was bad enough for them to see how Wilfried Zaha, their one-time winger, had been allowed to muscle in to make it 1-1 in the first-half. But it would get so much worse. Ten Hag had persisted with Sofyan Amrabat as a makeshift left-back, with all of his senior specialists in the position injured. And the second equaliser came down his side as Galatasaray simply ran through United, the substitute, Baris Alper Yilmaz, cantering forward before squaring for the excellent Kerem Akturkoglu, who rolled inside the far corner, nobody having tracked him. There would be another horror moment for the unconvincing Onana after his handling error for the first goal in Munich. This time, it was with his feet, his supposedly strong suit. When Onana tried to play a short pass out to Casemiro, he succeeded only in finding the Galatasaray substitute, Dries Mertens, whose eyes lit up as he surged into the area. Casemiro had no option but to make a desperate lunge, Mertens went down, it was a clear penalty and a red card for the United midfielder. Up stepped Mauro Icardi and Onana was mightily relieved when the striker dragged his kick past the post. There would be no reprieve for the 10 men. United’s defensive structure had disintegrated and, when Amrabat cleared upfield and Davinson Sánchez headed back, it was horrible to watch what happened next. Victor Lindelöf stepped up and watched the ball bounce past him and Icardi was through, Amrabat having played him onside. This time, he made no mistake. Onana had got away with a flap at a bouncing cross on 69 minutes, Zaha going back to Akturkoglu, who curled inches wide and Galatasaray might have added a late fourth, Sacha Boey and Icardi both spurning presentable chances. At least Ten Hag’s introduction of Antony as an 85th-minute substitute went under the radar; it was the winger’s first action since the accusations against him of domestic violence, which he denies. The full-time whistle was the prompt for boos from the home crowd, a reflex reaction born out of bitter frustration. Ten Hag’s empire is falling to pieces. It was a wild game from the outset, so open and – to put it bluntly – there for United to seize. Especially after Højlund’s first goal, a bullet header from Marcus Rashford’s cross after Casemiro had got United moving with a punt up the inside right. Højlund looked purposeful. He had teed up Bruno Fernandes at the outset; the United captain sent a side-foot wide. At 1-0, Mason Mount released Højlund and he was close to dribbling around the goalkeeper, Fernando Muslera. United remained so brittle in their defensive third and it had to be Zaha with the first equaliser. “Look at my face, am I bothered?” he had practically said on Monday when asked to reflect on his unhappy spell at United in 2013. He was certainly exercised after watching his side-on shot hit Diogo Dalot, bounce down and loop in, cupping his ears to the United support. It was an ugly one to let in because Zaha should not have been allowed to get that far. Sánchez’s long ball from the back bounced once and then again as Zaha got his body in between himself and Dalot. The finish was undercut by fortune. Zaha made his own by being stronger in the one-on-one than Dalot. Mount twice went close before the interval and, after it, United pushed. Rashford made a bad decision to square for Fernandes when clean through on 53 minutes, the move too obvious, Boey getting back to clear. But a United goal looked on, more chances coming. Højlund had one effort pulled back for offside before he stormed on to a loose back pass by the substitute, Sérgio Oliveira, outpacing Abdulkerim Bardakci to clip over Muslera. Cue the United collapse.