Barnsley's on loan midfielder Emil Hallfredsson may have played his last game for the club after it was revealed he has broken his foot.
The Icelandic international was signed on a season long loan from Italian side Reggina and has made 27 appearances and scored three goals, including the winner against Watford in February.
The 25-year-old was injured in a first half challenge at Bramall Lane in Saturday's 0-0 draw with Sheffield United.
Reds boss Mark Robins spoke of the loss:
"Emil has broken his fifth metatarsal. He will not feature again this campaign."
Meanwhile, midfielder Jacob Butterfield has signed a two-year contract extension with the club.
The 19-year-old has impressed for the Reds since coming through the Academy and has made 26 appearances in all competitions since his debut at Newcastle in the Carling Cup in August 2007.