If anything new can be thrown at Manchester United this early in the season, it is that they have tried hard to fix some important problems over the summer while ignoring another quite obvious one.

The ramifications of that were felt quite plainly and painfully in the sunshine at Old Trafford. United have invested in attacking talent to the tune of £200million since last season was capped so impotently and desperately in a Europa League final defeat by Tottenham in Bilbao.

The early evidence of this opening Premier League game suggests they have bought good players. Bryan Mbeumo, recruited from Brentford, was terrific down the right in a game that saw Ruben Amorim’s team play much of the progressive football. Matheus Cunha had his moments too, while the big forward Benjamin Sesko came off the bench as United went a little more direct late on.

For reasons unknown, however, United have not sought to fix their goalkeeping problem and here that decision bit them… and bit them hard.

United’s No 1 Andre Onana, so unimpressive over two previous seasons at the club, was dropped for this game and that tells its own story. The problem was that his replacement, Altay Bayindir, threw the winning goal into his own net on 13 minutes.

It was a setback from which United — manfully as they tried — could not recover.

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Riccardo Calafiori was the beneficiary for the visitors, nodding in from close range at the far post

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Man United’s Altay Bayindir failed to deal with Arsenal’s inswinging corner in the first half

At times, Arsenal’s physical approach to set pieces borders on the unlawful. Mikel Arteta’s team drew much praise for the detail and precision of their routines last season but that should not distract from the fact pushing and shoving and blocking at corners is not within the rules of the game. This one was comfortably the right side of the line, however.

The delivery from Declan Rice from the left side at the Stretford End was a good one and Bayindir — who has form for this kind of error — simply couldn’t cope with a legitimate challenge for the ball from Arsenal defender William Saliba.

The truth is that the United goalkeeper hardly got off the ground, managing only to paw the ball back towards goal, where Arsenal defender Riccardo Calafiori headed it over the line from a couple of inches. The ball was going in anyway.

So United were undone in familiar fashion and one wonders why the Old Trafford recruitment team have not addressed this obvious and damaging issue. Amorim says they won’t but maybe now they will. The transfer window closes in a fortnight.

It was a shame for Amorim and his team. United were superior and showed themselves to be rather better than they have previously been under their Portuguese coach.

After an hour, for example, they had enjoyed more than 65 per cent of the possession and much of the territory. That’s the way it used to be here at Old Trafford, in the days before authority and confidence gave way to fear.

United have relied far too much on the counter attack in recent seasons, lacking the players and wit to dictate rhythm and flow. That’s not the way it was on Sunday. They weren’t perfect. Far from it. The goal they conceded was wretched and teams who do things like that don’t tend to win things. No wonder Amorim was unusually prickly afterwards.

On the whole, though, United were more fluent and fluid and carried a threat. Mbeumo was particularly dangerous and on several occasions United managed to get him one on one against his immediate opponent, the goalscorer Califiori.

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Amorim made the shock decision to hand Bayindir the start after dropping No 1 Andre Onana from the squad

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Matheus Cunha impressed for the Red Devils as he was forced to play in an unfamiliar centre forward position

Another signing, Sesko, did not start the match but Arsenal’s new striker, Viktor Gyokeres, did play from the get-go. He was largely ineffectual and hauled off by Arteta after an hour. As soon as he was replaced by Kai Havertz, Arsenal improved.

United could have retreated after the disappointment of the goal but they didn’t. They fed Mbeumo well, even if when they went long to Cunha and Mason Mount — too often through the air — it didn’t work.

David Raya in the Arsenal goal wasn’t called on to make any fabulous saves. Indeed, not until he dived to palm away an Mbeumo header in in the 73rd minute did the Spaniard really do anything out of the ordinary.

But both Mbeumo and Cunha did bring routine saves from Raya in the opening half while left wing-back Patrick Dorgu struck the outside of the far post. Cunha then beat Declan Rice to the byline to cross low.

Arsenal, for their part, rarely threatened. Gyokeres was poor, Bukayo Saka was anonymous, and Rice and new partner Martin Zubimendi could not get a grip on the midfield. It was unlike the Gunners.

They have played much better than this here in recent seasons and not won. But they had the lead early and they managed to hang on to it.

The second half saw United threaten again through Mbeumo. Raya saved an overhead kick in the 65th minute and then the header. Into the latter stages and United did start to flag a little. Amorim made reasonable substitutions — Sesko, Amad Diallo, Manuel Ugarte and Harry Maguire coming on — but they didn’t have an impact on the game.

If anything, Arsenal started to look a little more comfortable and Rice thought he had crept a free-kick in at Bayindir’s left post late on, only for the ball to strike the side netting.

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It was a frustrating debut for Viktor Gyokeres, who failed to make his mark on the heavyweight clash

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Benjamin Sekso came on for his Manchester United debut but was unable to affect the game

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Amorim will be disappointed by another Old Trafford defeat but he will be encouraged by his team’s performance against one of the title favourites

There were flurries from United at the death. Saliba challenged Cunha from behind on the six-yard line and didn’t seem to take the ball. No offence was spotted by referee Simon Hooper.

Two late free-kicks were pumped into the Arsenal area and the second one — with 90 seconds left — won them a corner.

Predictably, Arsenal were strong in a way that United had not been earlier on. This stuff matters.