Papalii and Leilua both played for Samoa in a World Cup warm up match at Wagga in 2017, the start of a campaign where they packed on the pounds.

But this season couldn't be more different, with the dynamic duo both reaping the rewards of a huge pre-season.

They have been near Canberra's most consistent performers in a strong 5-2 start before Saturday's clash with Penrith at Wagga's Equex Centre.

"He's always had the potential to be that type of player and Origin leader (for Queensland)," Croker said of Papalii.

"The same with 'BJ' (Leilua), those blokes came back to pre-season in career best condition and to focus on football as opposed to getting blokes to lose kilos, you've seen the difference it's made to our season already."

Leilua was on the cusp of Origin in 2016 when the Raiders made the preliminary finals, and has started this year in the same vein.

His blockbusting runs which skittle opponents are easy to admire, but Croker said it's eradicating brain explosions and adding little disciplines to his game which has been his biggest change.

"The kick chases, being on the end of the line, pushing up in support, the little things a lot of people don't notice to be honest, but we notice," Croker said.

"They're those little extras Joey couldn't do if he didn't apply himself in pre-season. We've seen what Joey can do with the footy, for him to apply himself so well and get rewards for it is good.

"He wouldn't look out of place in that (Origin) arena."

Croker said the Raiders will be asking for trouble if they allow Penrith to offload at will after Manly's second-phase play hurt them badly in last week's 24-20 loss.

Superb defensively in previous rounds this year, the Raiders gave up 15 offloads as fatigue set in after losing the penalty count 13-5.

"Manly had a lot of second phase footy last week and if we give away the amount of penalties we did last week, we'll get the same result with Penrith," Croker said.

"They're a very good second phase footy side, they play that good brand of football and if you let them play they will.

"Our discipline's got to have to be a lot better than it was last weekend, and I think if we can control a lot of that we'll see more line speed and inside pressure.

"We just zapped ourselves this week with the penalties we gave away."

Raiders coach Ricky Stuart is wary of a Penrith side desperate to salvage their year after a disappointing 2-5 start.

"I know Penrith are desperate and they'll play that way," Stuart said.

"I thought they were very unlucky not to win (against Souths last week) and we'll have to be on our game if we want to beat them."

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