Newcastle second-rower Sione Mata'utia could miss the opening month of the NRL season after suffering a knee injury in last weekend's trial defeat to St George Illawarra.
The Knights on Tuesday confirmed a high-grade medial ligament injury in Mata'utia's right knee, ruling him out for six weeks.
There are two weeks left until the club's season-opener against the Warriors at McDonald Jones Stadium on March 14.
Mata'utia was shaping as a contender to start the year in the second row alongside Lachlan Fitzgibbon under new coach Adam O'Brien this season.
The Knights are already light on in backrowers in their top-30, with only veteran Aidan Guerra and uncapped rookie Brodie Jones their other options.
Elsewhere, Cronulla have also confirmed an ACL tear for hooker Cameron King, who is likely to miss the entire season.
It is a cruel blow for the 28-year-old, who was hoping to re-ignite his NRL career following a move from the Super League.
Sharks captain Wade Graham said it was shattering for his new teammate.
"They need to wait for bone bruising to go before they can do the surgery. It's not ideal for him. He came back, he got an opportunity with the club," Graham said at the Fox League launch.
"He trained well in the pre-season, playing his first game, and to go down in those circumstances is really sad. But the club will stick with him.
"It's unfortunate for him."
Graham himself is expected to take part in their final hit-out against Manly on Sunday despite picking up an ankle complaint during the All Stars match.
Winger Ronaldo Mulitalo has been ruled out with a knee injury he picked up in their trial defeat to Canterbury, but is likely to be available for round one.
Fullback Matt Moylan could be a chance of playing against the Sea Eagles in what will be his first appearance of the pre-season due to a hamstring issue.
Front-rowers Andrew Fifita and Braden Hamlin-Uele are also hopeful of getting their first minutes of the pre-season for the game in Kogarah.