Papali'i required treatment at Raiders training on Monday as he completed a light run, five days out from the clash with the Cowboys.
Initially hurt while warming up for Canberra's final pre-season match, Papali'i played 20 minutes of that game against Canterbury.
But the injury hasn't responded to treatment and the Queensland State of Origin prop has been in a race against the clock for round one.
"It's all good, obviously just a little tweak in my calf," Papali'i said on Monday.
"Doing all I can to be ready for Saturday. I should be alright. I had a little run today, it wasn't too bad.
"Just taking it day by day. Hopefully be right for round one."
One of the most damaging forwards in the NRL when at his best, Papali'i's absence would be a massive blow for the Raiders.
It comes as questions still surround the make up of the Raiders' pack.
Joseph Tapine wore the No.13 in Canberra's last pre-season match against Canterbury with Emre Guler playing front row, but is adamant he wants to play as a prop this year.
Tapine enjoyed the best year of his career last season as he started in the front row each game, able to focus more in his running game rather than ball playing.
"I'll step back into No.10 hopefully," he told AAP last week.
"I've talked to Stick (coach Ricky Stuart) and I think I'll be starting in the front row with Papi on the weekend.
"I was named at No.13 (for the second trial game) but I told Emre (Guler) I wanted to practice prop because that's the position I'll play this year.
"I prefer playing prop, in the World Cup they wanted me to do more ball-playing but I stuck to my guns and just ran the footy more and tried to offload.
"I try not to change. I think I'm more of a prop these days, lock has turned into more of a ball-playing role."
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