Canberra forward Dunamis Lui.

They are big shoes to fill but Raiders forward Dunamis Lui has backed himself to take on extra responsibility after being called into the starting side for the suspended Joe Tapine.

Lui has been understatedly consistent for Canberra coming off the bench for much of the year, especially in the wake of suffering an ACL injury in 2018.

The opportunity to prove himself against the Manly Sea Eagles on Friday night comes at a good time for the off-contract Lui. The departure of Junior Paulo (Eels) and Shannon Boyd (Titans) at season's end will create opportunities at the club. 

Lui knows he faces a tough task in having to cover for one of the best young forwards in the NRL.

"It's going to be a massive challenge for myself, with Tapis out and me being pushed into the starting line-up. I'm thankful for the opportunity," Lui said.

"But there's a massive job for me to start the job well, it's going to be a really big challenge."

The incentive to carve out a new role for himself is also there as the salary cap puts the squeeze on the Raiders.

Lui said he couldn't shed any light as to when a possible contract extension might be forthcoming but did say he would pledge his future to Canberra if it was possible.

One of the Raiders forwards earmarked for bigger things at the club is Liam Knight, who again has been called up to the bench due to the Tapine suspension.

The 23-year-old admitted it was hard bouncing between the Intrust Super Premiership and the NRL, but did not complain if it meant getting a chance to prove himself at the top level.

"Sometimes it does make it a bit harder, but whatever Ricky needs for the team, whatever is best, that's what I want to do," he said.

"I'm really happy to be back in after having a couple of weeks out at 18th man, but really hoping to do my job and stay in there for a few weeks this time."

With two losses in a row and the side sitting two wins outside the top eight, Lui said the side cannot let any more chances at victory slip through their fingers if they want to be playing in the post-season.

"I think last weekend we were a bit flat, that's no excuse but this week we really have to bring that energy," he said.