Manchester United manager Erik ten Hag revealed Jadon Sancho was dropped for the trip to Arsenal due to poor training performance.
The England winger did not travel to north London for the match, where United conceded two late goals to fall to a 3-1 loss at the Emirates Stadium.
Sancho, 23, had previously come off the bench in the first three Premier League games of the new season.
But Ten Hag accused the forward of not reaching the “level” required to be part of his matchday squad against the Gunners.
“Jadon, on his performances in training we did not select him,” the Dutchman said after the defeat.
“You have to reach a level every day at Manchester United and we can make choices in the front line. So for this game he was not selected.”
Sancho has struggled for consistent form since moving to Old Trafford for Borussia Dortmund for £73million in 2021.
He has scored nine league goals and provided just six assists in his 58 appearances for the Red Devils and will now have to prove himself to Ten Hag to get back in his thinking for the visit of high-flying Brighton after the international break.