Derby's on-loan striker James Wilson has returned to parent club Manchester United due to a serious knee injury.
Wilson, 20, sustained the injury during training with Derby on Monday and both clubs are waiting to learn the full extent of the damage.
'On-loan James Wilson has returned to #MUFC for assessment on a significant knee injury sustained during Derby County training on Monday,' United stated on Twitter.
Wilson joined Derby on a season-long loan in August and has made four appearances for the Sky Bet Championship club, including three starts.