Castleford's preparations for the new season have been rocked by a serious injury to playmaker Luke Gale.
The England international ruptured his Achilles during a training session on Saturday, shortly after undergoing knee surgery.
Gale, 30, also missed a chunk of last season because of a serious knee problem.
"Luke has suffered a suspected ruptured Achilles tendon during training over the weekend," Tigers' director of rugby Jon Wells said in a statement.
"He will be seeing a specialist to assess the seriousness of the injury but unfortunately the prognosis doesn't look great.
"The whole club is gutted for Luke, who had been progressing really well following off-season surgery to his knee.
"This is likely to be another significant setback for him but having known Luke for many years I know that he is an extremely strong character and a resilient member of our squad who will be doing everything he can to overcome this latest hurdle and return fit and healthy to the Tigers fold in the future."