There are Old Trafford debuts to savour. Wayne Rooney’s hat-trick against Fenerbahce, for instance, or Anthony Martial’s solo strike against Liverpool. A teenage Cristiano Ronaldo’s precocious display of trickery against Bolton. A similarly young Marcus Rashford’s two-goal emergence onto the scene against Midtjylland. Federico Macheda’s injury-time decider against Aston Villa was perhaps the goal that swung a title race. It is safe to say Andre Onana and Mason Mount’s United bows at Old Trafford do not belong in that category. They were introductions to forget, matches to be banished from the memory bank, moments that can at least be caveated with the knowledge that, as they happened in pre-season, there was an irrelevance to their ignominy. But these were inauspicious ways to start life at United’s home ground. Their £47 million goalkeeper was lobbed from perhaps 47 yards. Their £55 million midfielder missed an open goal. The £72 million striker, Rasmus Hojlund, was unveiled to smiles and applause but he is injured and will miss the start of the season. Erik ten Hag has landed his three major summer targets. They were not hired for one to be sidelined or humiliated. As United recovered to beat Lens 3-1, a three-goal comeback was preceded by a tale of three signings. The boyhood United fan Hojlund took the field first, though a problem sustained in pre-season with Atalanta means it is a few weeks before he does in earnest. He will be charged with converting chances. When Mount made a forceful run from deep into the box, the clearest of opportunities materialised. Bruno Fernandes’ cross-field ball was superb, Alejandro Garnacho centred and Mount only had to apply the finishing touch. But he swung his left foot and the ball hit his standing leg, his right. It was a glaring miss. Then came an extraordinary opener. United savoured a No. 7 lobbing a goalkeeper from the environs of the half-way line when it was David Beckham. Not when it was Florian Sotoca, a 32-year-old journeyman of a French forward. It was not entirely Onana’s fault, but it was a product of the shift in style since David de Gea’s departure. It was apparent from the off. There were cheers when, after barely 80 seconds, Onana came out of his box to get involved in a passing move. De Gea rarely did that. There was evidence of his confidence, too, with a cheeky header to Diogo Dalot when, had he held back a yard or two, he could have caught the ball in his box. On each occasion, his willingness to double up as the 11th outfield player showed the extra dimension he can offer United. But it was also a reason why Onana was on the edge of his area when Dalot misplaced a pass and Sotoca took aim with a combination of ambition and precision.c Backpedalling, flailing in thin air, Onana ended up in the back of the net. So did the ball. He had to untangle himself. It is a form of embarrassment that is an occupational hazard, part of the risk-and-reward equation for a footballing goalkeeper. De Gea probably would not have conceded that goal, because his starting position would have been five yards further back. Perhaps the Cameroonian has exacerbated the differences with his predecessor; his pre-season has been notable for how far he has strayed from his goal. United have gone from one of the most conservative keepers to one of the boldest. There is a showman in Onana; when a last-minute shot looped up off Lisandro Martinez, he made a flamboyant save, but if De Gea was undermined by his poor passing, the other issue was his errors. Meanwhile, a team who had lost their previous three pre-season games – albeit one with a youth side to Wrexham – went from a goal down to 3-1 up with a quick turnaround. First Marcus Rashford equalised with a deflected shot. The Mancunian operated as the centre-forward, a role that, with Hojlund injured, he is likely to occupy at the start of the season. Then Antony, who had provided the pass for Rashford’s goal, scored the second with a dink over goalkeeper Brice Samba following a ball from the electric Garnacho. Finally, Rashford’s header deflected in off Casemiro. They face Athletic Bilbao in Dublin on Sunday and return to Old Trafford to start their league campaign against Wolves. And then, Mount and Onana must hope, their first competitive action at Old Trafford will give them something to recall more fondly. Read More Manchester United complete £72m transfer of striker Rasmus Hojlund Marcus Rashford: Wayne Rooney wants me to break his Manchester United record A new era for old empires? How a summer of rebuilding could change the Premier League