Castleford prop Jonathan Walker could miss the rest of the season after dislocating his knee in an innocuous-looking challenge against Huddersfield.
Walker was carried off in the second half following a tackle by Eorl Crabtree, and Castleford coach Terry Matterson revealed it could be serious.
"It doesn't look good for Jonny," said Matterson, after Sunday's 40-18 defeat. It looks like his season is over."
"It was only his second game back after 13 weeks out.
Castleford have endured an injury-hit season but their fortunes had taken a turn for the better of late until Walker's moment of misfortune.
"I was starting to get pretty excited about having some numbers back so this injury is another blow," said Matterson.
Walker was not the only player to suffer injury on Sunday.
"Danny's gone for some X-rays and it looks like he'll be out for a while," said Huddersfield coach Nathan Brown. "It's unfortunate because he'd earned the right to play for England."