Northern Ireland defender Jonny Evans will be sidelined for the "next few weeks" due to a thigh strain he suffered in the first half of United's 4-3 Champions League defeat at FC Copenhagen.
Manchester United said late on Friday.
He joins a lengthy injury list at United, who remain without defenders Lisandro Martinez, Luke Shaw, Tyrell Malacia and midfielder Casemiro.
The 35-year-old will miss Northern Ireland's final Euro 2024 qualifiers against Finland and Denmark. Northern Ireland, who sit fifth in Group H with six points, travel to Finland next Friday before hosting Denmark on November 20.
Evans rejoined United on a one-year deal in September, eight years after leaving Old Trafford and has started five league games.
United lie in eighth place in the top-flight after picking up 18 points in 11 matches and host promoted Luton Town later on Saturday.
Substitute Jhon Duran scored two late goals as Aston Villa fought back to salvage a 3-3 home draw with Liverpool on Monday and take a significant step towards a place in the Champions League next season.
Arsenal's Leandro Trossard capitalised on dreadful defending to secure a 1-0 win against Manchester United that saw the Gunners climb back to the top of the Premier League, ensuring the title race will be decided on the final day.
UAE Team Emirates rider Tadej Pogacar has retained his overall lead after Dutchman Olav Kooij won stage nine of the Giro d'Italia on Sunday, pipping Jonathan Milan by half a wheel right at the finish line in a breathless sprint at the end of a 214-km ride from Avezzano to Naples.
Rory McIIroy claimed his fourth Wells Fargo Championship after a superb back nine saw him finish -17 par having trailed by two shots after seven holes.