Harry Maguire appeared to suffer a groin injury during the first half of Manchester United's must-win Champions league clash against Bayern Munich on Tuesday night.
The centre-back was running with the ball before he immediately pulled up in some discomfort, holding his groin.
The 30-year-old received some treatment on the side of the pitch and managed to play on for several minutes before he was substituted for Jonny Evans.
While the nature of the injury is not yet confirmed, Maguire could now be a doubt for United's crunch match against Liverpool at Anfield next weekend.