Arsenal continue their good form on set pieces, thanks to Riccardo Calafiori's winner against Manchester United. (Photo by Stuart MacFarlane/Arsenal FC via Getty Images)

MANCHESTER, England -- Altay Bayindir's 13th-minute mistake gifted Riccardo Calafiori the only goal as Arsenal beat Manchester United 1-0 at Old Trafford on Sunday.

United were the better side for long periods. Still, despite handing full debuts to summer signings Bryan Mbeumo and Matheus Cunha -- before introducing Benjamin Sesko for the final 25 minutes -- Ruben Amorim's side failed to find the net.

Amorim admitted before kickoff that goalkeeper André Onana was fit enough to start, but opted for Bayindir, and that decision backfired as his mistake proved to be the crucial moment.

- Premier League recap: Arsenal's Calafiori gets winner against United - Chelsea ratings: Palmer, Gittens, Pedro all 4/10 in drab draw with Palace - Premier League Top 50: Ranking best players before 2025-26 season

Arsenal gave debuts of their own to Martín Zubimendi and Viktor Gyökeres but never fully got into stride. Patrick Dorgu hit the post in the first half while Cunha was regularly a threat, turning Ben White brilliantly at one point in the second half.

Amorim called on Sesko to find a way back, but ultimately United came up short as Arsenal started their quest for a first Premier League title since 2004 with a precious win. -- James Olley

Arsenal's squad depth shows in win

One important driver of Arsenal's transfer business this summer was to increase the squad depth available to Mikel Arteta, and it was notable in the substitutions he made at Old Trafford.

Kai Havertz and Myles Lewis-Skelly were regular starters last season, Jurriën Timber and Mikel Merino are strong options, and Noni Madueke is a £52 million summer signing from Chelsea.

It makes a change from relying on fringe players Arteta perhaps does not entirely trust, and the Gunners believe they are better insulated now should an injury crisis befall them as it did last season.

Their second-half performance was more of a rearguard action than anything else, but the physicality they were able to introduce off the bench helped maintain their level. The decision to select him ahead of Lewis-Skelly at left back was something of a surprise, but while Calafiori affected the game in a way Arteta probably didn't expect, the defender seems to like scoring in Manchester.

Think back to the superb goal he scored against Manchester City in September. -- Olley

United grapple with same goalkeeping issues

Whether United need a new goalkeeper has been a topic of conversation all summer. It's not going away, particularly after Bayindir's howler here.

He got the nod in goal because Onana has missed all of preseason with a hamstring injury. Onana is fit again but managed only three full sessions with the team last week. Onana has hardly been convincing since his move from Ajax two years ago. And if this was Bayindir's big chance to impress, he fluffed his lines.

He got trapped on his line when Declan Rice's corner came over. Not strong enough to bully people out of the way, he could only flap at the ball, and Calafiori had the simplest of headers on the line.

United have tried to quiet talk of a new goalkeeper in the past 10 days. Club sources have distanced themselves from a move for Gianluigi Donnarumma, even though he's available from Paris Saint-Germain. They did make a loan bid for Emiliano Martínez earlier in the summer, but it was turned down by Aston Villa. There are still a couple of weeks left in the transfer window.

United, though, insist that if there is any more money to spend, it is likely to go for a midfielder. Maybe Bayindir's mistake and continuing doubts about Onana will convince them that a goalkeeper should be the priority. -- Rob Dawson

Gyökeres has room for improvement

There was an understandable focus on Gyökeres at Old Trafford after his €73 million move from Sporting CP.

Many thought he would one day sign for United, given his connection with Amorim in Portugal. But Arsenal made the move after months -- if not years -- of Gunners fans crying out for a clinical center forward to take them one step further and win a Premier League title.

Nobody should judge him after one game, but it is still fair to say there is room for improvement. Despite one or two dangerous moments -- and a fine first-half cross for Gabriel Martinelli -- Gyökeres was substituted on the hour mark, having failed to register a single shot at goal.

Part of that was down to Arsenal's conservative approach, but early in the second half, Gyökeres found himself with space and a chance to bear down on goal. Instead, he fell over the ball and fouled Casemiro. Gyökeres ended with 21 touches and four passes completed out of nine.

He will surely improve. But the absence of a shot is a surprising anomaly. In the previous two Primeira Liga seasons with Sporting, he recorded at least one shot in all 66 games played. Gyökeres, 27, last failed to register a shot in March 2024 against Atalanta in the UEFA Europa League. -- Olley

Steve Nicol thinks some of the criticism of Gyokeres and Sesko is a bit overblown after Arsenal's 1-0 win over Man United.

United improved but not enough

United lost again at Old Trafford under Amorim, but this was a lot different from some of those horrific defeats last season. Amorim promised fans a better team and -- at least in Week 1 -- he delivered. Cunha was bright and linked up well with fellow summer signing Mbeumo.

The 3-4-3 system functioned well, giving wing backs Diogo Dalot and Dorgu space down the flanks. Casemiro and Bruno Fernandes even held their own in the midfield battle against Rice, Zubimendi and Martin Ødegaard.

But tight games are decided by fine margins, and United were on the wrong end of them. Bayindir had barely anything to do except palm a corner right onto Calafiori's head. Amorim isn't the type to take too many positives from a defeat. This, though, should feel like a step in the right direction.

If United can back up this performance with wins over Fulham and Burnley ahead of the derby against Manchester City on Sept. 14, there will be renewed optimism around Old Trafford. -- Dawson

Steve Nicol believes Man United still need to do more to score goals following their 1-0 defeat to Arsenal.

Writing on the wall for Højlund

United and Amorim could not be sending a stronger message to Rasmus Højlund.

After the striker was an unused substitute in the final summer friendly against Fiorentina, he wasn't even on the bench against Arsenal. Joshua Zirkzee hasn't been fit enough to play at all in preseason, but he was still named in the matchday squad. It looks very much like Højlund's time at Old Trafford is up.

He's in a difficult position. United is his dream club, and he doesn't want to give it up without a fight. On the flip side, with the way he has been handled in the past week, it looks like he's not part of Amorim's plans. United want £40m for Højlund, but it's more likely that they'll have to accept an initial loan with an option or obligation to make the move permanent next summer.

There's interest from AC Milan, and you'd expect the Italian side to firm it up after seeing the 22-year-old sit in the stands watching his teammates face Arsenal.

Of course, Højlund wouldn't be the first player to battle his way back into a manager's thoughts. But after being axed here, it will be a surprise if he is still a United player on Sept. 2. -- Dawson