The beloved prop forward rolled his ankle at training on Friday and has been wearing a moon boot in a bid to be fit for the Raiders' week-one finals match at GIO Stadium on Sunday.
The minor premiers confirmed news of Papalii's injury on Monday, just as they entered the next phase of preparations to claim a first premiership since 1994.
Papalii is expected to be named in the team list on Tuesday but the Raiders will not take any risks with the 33-year-old given they have the double chance in finals and plenty of forward depth.
But it would be devastating for the Raiders to lose their spiritual leader, who has been synonymous with the club since his NRL debut in 2011.
Papalii is in the midst of an excellent season, and in June passed Jason Croker to become the most-capped player in Raiders history.
He has become noted for his leadership at the Raiders, a quality that shaped as crucial this September as young stars Kaeo Weekes and Ethan Strange play finals for the first time.
Papalii recently helped an inexperienced Queensland team take out the State of Origin series, coming out of Origin retirement for the decisive third match of this year's series.
He is also one of only three players remaining from the Raiders' last grand final appearance in 2019 and was the star of the preliminary final win that confirmed their berth in that decider.
Papalii's injury could pave the way for English recruit Matty Nicholson to retain his spot in the Raiders' 17 against the fourth-placed Broncos.
With most of the side's big-name players rested, highly-rated Nicholson faced the Dolphins on Sunday for his first game since being struck down by serious leg injuries in May.
Middle forward Trey Mooney, expected to join Newcastle at the season's end, is another option if Papalii needs time out.
Captain Joe Tapine said the Raiders were looking forward to their first home final at GIO Stadium since 2020.
"If we play our footy and create energy around it, I'm looking forward to the challenge and the boys should embrace it," he said prior to news of Papalii's injury.
Papalii's front-row partner believed the Raiders still had new heights to scale this finals series.
"I don't think you'll ever see the best of any team. You can't be perfect, but there's definitely room for us to be better. I think hopefully that game is the grand final," Tapine said.
10°C