Castleford forward Grant Millington will miss the Tigers' Challenge Cup semi-final and possibly the rest of the season with a knee injury sustained in last week's First Utility Super League draw at Hull FC.
The loss of the ball-handling Australian is a major blow for the Tigers, who have also lost second-rower Weller Hauraki to a two-match suspension.
Millington, who has been an ever-present in Castleford's impressive Super League campaign so far this year after producing his best form for the club, is facing a six-week spell on the sidelines which would also rule him out of a trip to Wembley if the Tigers overcome Widnes Vikings on Sunday week.
Castleford coach Daryl Powell said: "The news is disappointing for both the team and for Grant personally but our medical staff will be working exceptionally hard to get Grant back as soon as possible."
Millington added: "Obviously I'm really disappointed with the injury. It's always frustrating to have any time out from playing but to be told I will miss the biggest game of the year so far in the Challenge Cup semi-final was pretty hard to take.
"I'll be working hard with the medical staff and doing everything that I can over the next few weeks to get back on the playing field as quickly as possible."
Powell says the club are considering appealing the ban on Hauraki, who was found guilty of using his knees in the tackle during the game at the KC Stadium.