Penrith Panthers second-rower Luke Garner has suffered a rib injury, with Ivan Cleary confirming he wasn't dropped for this weekend's game against the Canberra Raiders.

Team lists named on Tuesday for Round 5 fixtures brought with them plenty of surprises, but among them was the replacement of Garner in the second-row, with Scott Sorensen to join Zac Hosking in a new-look edge pairing for the Panthers.

That comes with Liam Martin also still missing as the New South Wales State of Origin and Australian Kangaroos international representative continues to battle a hamstring problem.

While Martin is due back next weekend against the Manly Sea Eagles for the men from the foot of the mountains, Cleary told the media that due to the nature of Garner's rib injury, it's tricky to put a return timeline on him at this stage.

“No (he wasn't dropped). He's injured. He played with a rib injury last week and it's still there,” Cleary said.

“Ribs are a bit hard to put a timeframe on. He shouldn't be out for too long.”

It comes as Penrith head into the game against the Rabbitohs with a one and two record following last week's thrilling loss to the Parramatta Eels in golden point.

Sorensen's promotion to the starting side will weaken the overall depth of the Penrith forward pack, with the New Zealand international being an integral part of Penrith's back-to-back premiership charge in his role off the bench.

While he has previously spent most of his time on the edge, Sorensen's time on the bench at Penrith has seen him play plenty of time in the middle third, and his work ethic has been praised as one of the best in the NRL.

His chance in the starting team will likely see him play close to the full 80 minutes this weekend, which will be a considerable step up in responsibility.

Penrith's game against the Raiders - to be played in Canberra - kicks off at 6pm (AEDT) on Friday evening.