Barnsley striker Iain Hume is in hospital after suffering a fractured skull in Saturday's derby defeat by Sheffield United.
Hume was hurt during the first half of the Tykes' 2-1 loss after a clash with Blades captain Chris Morgan.
The Canadian felt groggy after the game at Oakwell and his condition deteriorated as the weekend progressed.
He was taken into hospital for surgery and the 25-year-old is currently being kept in a high dependency unit.
Tykes manager Simon Davey said: "He got caught in the face with an elbow.
"He couldn't move his neck. His neck was stiff and his cheekbone's not in the same shape it was when he started the game."
Morgan was booked in the incident which caused the injury and the Blades have sent a message of support to Hume.
The statement on the club's official website read: "Sheffield United are saddened and concerned to hear that Barnsley striker Iain Hume is being monitored in a high dependency unit following last Saturday's fixture and we wish him a speedy and full recovery."
Hume joined Barnsley in a £1.2million deal from Leicester City in the summer and has scored four goals in 16 appearances.