Sheffield United's on-loan defender Kyle Bartley is likely to be out for at least six weeks after suffering a fractured cheekbone.
Bartley was hurt during an aerial collision with Nottingham Forest striker Dele Adebola during the Blades' 1-1 draw at the City Ground on Tuesday night.
The 19-year-old, who is on loan from Arsenal, was taken to hospital at the end of the game and Blades boss Gary Speed confirmed the severity of the injury.
"It's a fractured cheekbone," said Speed. "We knew that straight away.
"You could see it was depressed - I saw from where I was. I've done it myself.
"Hopefully he will be back as soon as possible. Usually if there are no complications it's six to eight weeks, but it depends how bad it is."
Speed cleared veteran striker Adebola of any blame, adding: "It was a clash of heads. I know Dele and he's not that type.
"It was a bit late, Kyle got there first, but it was certainly an accident.
"Dele is a big unit, so it's unfortunate."
Bartley has made nine appearances since rejoining the Blades on a season-long loan after spending a spell with the Championship club last term.