Herrera had been in good form this season before picking up an injury which caused him to miss four Premier League games on the bounce for Louis van Gaal.
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When the 25-year-old returned for Van Gaal’s side on Saturday against Hull City, he pulled out a very good performance, completed 91% of his passes and creating two chances.
With Man United already without Wayne Rooney, Daley Blind and Angel Di Maria, Herrera’s knock may be another worry for Van Gaal’s ridiculously long injury list.
Man United fans will be praying that the injury was nothing too serious and that he was taken off as a precaution ahead of their trip to Southampton next Monday evening.