Back-up hooker Benaiah Ioelu is the leading candidate to replace Connor Watson on the Roosters' six-man bench for Sunday's NRL grand final against Newcastle.
Watson, 30, was ruled out after an independent doctor declined to overturn his Category 1 head injury assessment. Nine's Danny Weidler confirmed the decision on Friday afternoon.
The injury came in the Roosters' preliminary final win over the Dolphins, when Watson was knocked unconscious and left the field after barely a minute.
Initially assessed as a Category 2 incident, the head knock was later upgraded to Category 1, triggering a mandatory 11-day stand-down. The Roosters challenged, citing Watson's successful tests in the sheds and after the match, and the absence of later concussion symptoms.
The club sought an exemption so he could play, but Watson failed tests with the NRL's independent neurologist on Thursday. Medical experts have suggested 11 days may be insufficient after a Category 1 injury involving loss of consciousness.
Coach Trent Robinson had hoped Watson would be cleared. "He had an appointment this morning that went well and he has another one this afternoon," he said. "He deserves to play and we want him to play."
Watson is expected to join the Dragons next season and the PNG Chiefs in 2028, making Sunday likely his final opportunity to play for the Roosters.