United are still assessing the full extent of the injury but acknowledge the 28-year-old left-back will be out for a number of weeks.
He will miss England’s games against Ukraine and Scotland next month.
Manager Erik ten Hag already has injury problems at left-back with Tyrell Malacia also out.
Meanwhile, Brandon Williams has been loaned to Championship side Ipswich Town.
Diogo Dalot has played on the left in the past but it is a problem Ten Hag can do without as he looks to navigate his way through United’s unconvincing start to the season.
United beat Wolves 1-0 before losing 2-0 to Tottenham.
Manchester United are also currently without midfielder Mason Mount and forward Rasmus Hojlund through injury.
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- Erik ten Hag has confirmed Manchester United are aiming to sign a left-back but suggested they would not reinforce their attack before the transfer window closes on Friday.
Luke Shaw is understood to be out with a muscular injury for months, rather than weeks, and fellow left-back Tyrell Malacia is unavailable until after the September internationals.
United let reserve left-back Brandon Williams join Ipswich Town on a season-long loan on Thursday while 20-year-old Spaniard Alvaro Fernandez could also leave before next Friday’s transfer deadline.
Ten Hag has been without a fully-fit striker in United’s opening games against Wolves and Tottenham but Rasmus Hojlund has started team training and could make his debut against Arsenal next Sunday.
Also read: United in the market for left-back after Shaw injury
Anthony Martial came on for his first appearance in 12 weeks in the defeat at Spurs and Ten Hag believes United have ample cover up front, despite managing one goal from open play in their last three games.
When asked if he felt United were short in attack, Ten Hag replied: “No. We have seven front players and young talent coming up, as we’ve seen in pre-season, who are getting close.
“Rasmus will be available from next week onwards. Rasmus, Anthony Martial, we have cover. We have Rashy as well there. We have enough quality players to cover that position.
“It can be (that United sign a left-back). I think we always have to anticipate on situations. If there are opportunities then yes, but it has to be the right player otherwise we have to deal with the current squad.
- “It can be (that United sign a left-back). I think we always have to anticipate on situations. If there are opportunities then yes, but it has to be the right player otherwise we have to deal with the current squad
- “We went through the scenarios before the season and if it happened, we have the solution.”
Jadon Sancho is in contention for a first start of the season for the Premier League visit of Nottingham Forest on Saturday and Facundo Pellistri is pushing for a full league debut.
Right-sided forward Amad is still nursing a knee injury and is not due to be back until next month at the earliest
