Kruise Leeming is set to miss three to four months of action following knee surgery.
The new Leeds hooker, who has yet to make his debut for the club, suffered a pre-season injury that the club initially confirmed would rule him out for the start of the season.
But recovery has not gone as hoped and now the England Knights talent is set for an extensive spell on the sidelines.
“Kruise has been a real difficult one,” head coach Richard Agar told BBC Radio Leeds.
“It was a pretty innocuous, no one near him, he put a step on before contact and had some problems with his knee.
“It took a while to get the full prognosis, we have had an attempt at rectifying it without surgery, we didn’t want to do it immediately because he has a good knee, once you go inside it’s not as good as before but unfortunately the final conclusion was he needed surgery and sizeable surgery at that.
“He’s had a resolution to it, he’s been down to London and had it done by the top surgeon in the country. It could be 12-16 weeks but we’re looking at the top end at that.
“So yeah, it’s a blow, it’s a blow to him. He’s an ultra professional, driven young player. We’ll miss him, but we’ll get him right, we always signed Kruise for the long-term and he’ll do everything rehabilitation wise to get right.”
Agar confirmed winger Tom Briscoe was ahead of schedule and could return from his ACL injury in 5-7 weeks, which would put him two months ahead of schedule, while Stevie Ward has not started his return to play protocol from a delayed concussion.