Castleford duo Oliver Holmes and Will Maher will miss the entire pre-season programme after suffering injuries.
England international Holmes has picked up a shoulder injury. He first picked up the injury at the back end of the season and during his time with England Knights.
Holmes, who played 27 games for the Tigers in 2018, will now miss a few of the opening rounds in 2019.
Castleford’s physio Matty Crowther said: “Oliver Holmes has been nursing a shoulder injury for quite some time, which people haven’t realised.
“He came back from the tour with England Knights and we got him scanned and realised his shoulder was a little bit worse than we thought and he needed surgery on it.
“So, Oliver is going to be missing for three to four months but we feel like as a club that this is the right time to do it and get him back for maybe a month into the season, ready for a very strong finish from Oliver.”
Maher, 23, reported back for pre-season with the rest of the squad but ruptured his pectoral muscle in his first session.
He has undergone surgery already and is on the road to recovery.
Crowther added: “Unfortunately, on day one of pre-season Will Maher ruptured his pectoral muscle so he’s going to be out for a while.
“He needs surgery. He’s never injured is Will, he’s never missed any games through injury it’s just a very unfortunate injury on day one.
“The fortunate part is that he’ll be back within three months, so it will take him the full pre-season.”
Holmes and Maher have both been ruled out for three to four months.