Riccardo Calafiori scored the only goal after the Italian defender pounced on a huge mistake by United’s stand-in goalkeeper Altay Bayindir.
Despite promising debuts, Matheus Cunha and Bryan Mbeumo failed to find the net, while substitute Benjamin Sesko could not make Arsenal pay for not pursuing their interest in the Slovenian.
After finishing second for the past three seasons, the pressure is on Arsenal boss Mikel Arteta to deliver the club’s first league title in 2003/04.
The Spaniard was left to depend on his reliable defence and goalkeeper David Raya to secure a huge three points as the visitors never got going as an attacking force.
Only four other teams scored fewer than United’s 44 goals in 38 Premier League games last season as the English giants endured their worst campaign for 51 years, finishing 15th in the table.
The new arrivals have at least lifted the mood around Old Trafford and the majority of the 75,000 fans in attendance could at least leave encouraged by the performance of Ruben Amorim’s men.
Cunha and Mbeumo unsettled Arsenal’s normally unflappable centre-back pairing of Gabriel Magalhaes and William Saliba early on.
However, United’s good work was undone by a glaring error from Bayindir, who was deputising for the injured Andre Onana.
Credit: rfi.fr