Robin van Persie is set to miss eight games
The Dutchman, 30, was injured while taking the corner that led to Phil Jones’ winner against Champions League opponents Shakhtar Donetsk on Tuesday.
Van Persie has endured a campaign disrupted by injury so far after suffering toe and groin problems. Last weekend, he had returned from a month-long absence in the 1-0 defeat to Newcastle.
He arrived at Old Trafford for £24m from Arsenal in August 2012 and scored 26 goals last season as United claimed the Premier League title.