Panthers halfback Nathan Cleary wrote "I'll be back" in an Instagram post thanking supporters following surgery on his broken left ankle.
Billy Slater said tackling rules contributed to the way Phoenix Crossland approached the tackle that injured Cleary.
Phoenix Crossland will face the judiciary on Tuesday night in an unlikely bid to play in the NRL grand final.
Penrith Panthers star Nathan Cleary has vowed to return after his 2026 season was cut short on Sunday, thanking fans for their support from his hospital bed.
The 28-year-old suffered a compound fracture of his left ankle in the Panthers' NRL preliminary final defeat against Newcastle, ruling him out of the Kangaroos' World Cup campaign.
The Panthers fell apart to lose to the 12-man Knights, 22-14.
On Monday, the star halfback posted a photo from hospital, with his left leg bandaged following surgery.
"Surgery done," he wrote on Instagram, with a photo of him smiling and giving thumbs up to the camera.
"Thank you so much to everyone that has reached out, the support has been unbelievable."
The injury cast a pall over the Sydney Olympic Stadium, with Panthers players visibly distressed on field while their star was being treated by medical staff.
"He's one of my best mates," Panthers captain Isaah Yeo said post-match.
Cleary's father, coach Ivan Cleary, also said that seeing his son in such a state at half-time was "emotional".
Cleary came onto the field 25 minutes into the first half, but only lasted 10 minutes before Newcastle hooker Phoenix Crossland fell onto his ankle in a tackle.