South Sydney will be without forward John Sutton for four months and half-back Adam Reynolds fox six weeks after they were diagnosed with a ruptured a pectoral muscle and fractured jaw respectively.

Sutton will be unavailable until round 17 for the Rabbitohs after coming from the field late in their 42-10 win over arch-rivals the Sydney Roosters, while Souths expect to be without Reynolds for six matches after their injuries were confirmed on Monday.

Canberra Raiders pair Aidan Sezer and Blake Austin will also miss six weeks of NRL action due to injury, as will Sharks and New South Wales skipper Paul Gallen.

Regular five-eighth Luke Keary will likely return from suspension to replace Reynold's for Saturday night's clash with Newcastle, partnering with Cody Walker in the halves.

Walker looked comfortable on his NRL debut laying on an early try and combining well with Reynolds, impressing coach Michael Maguire.

"He was good Cody and with the changes on the field, he just adapted," Maguire said.

"It is just the practice he has shown throughout the season and it has shown on the field."

Gallen sidelined for more than a month

Cronulla captain Gallen remains upbeat despite confirmation he will miss up to six weeks after suffering knee ligament damage in the Sharks' 20-14 loss to the Cowboys.

While Sharks coach Shane Flanagan breathed a sigh of relief that his 34-year-old skipper did not have a season-ending problem, it is yet another blow for Gallen who managed to play just 27 of the Sharks' 50 games over 2014-15.

His history of injury last year led his club to ask him to stand down from representative football so he could spend more time on the park for the Sharks in the twilight years of his career.

Off-contract at the end of this year, Gallen is contemplating whether to seek a one-year extension that would take his career into a 17th season.

He said on Monday the latest setback would not affect his decision, which he is expected to make before Origin I, and said it was not a sign his time in the game was drawing to a close.

Out for six weeks ... Paul Gallen (left). ( AAP Image: Paul Miller )

"I'm not talking about (the end of my career)," Gallen said.

"It's an injury. (Bulldogs hooker) Michael Lichaa is 21 and he did the same thing on the weekend.

"It's a contact sport and it's the game we play and that's the way it is."

In Gallen's absence, Michael Ennis and Wade Graham will serve as co-captains while Joseph Paulo and Jesse Sene-Lefao shapes as possible replacements in the Sharks 17.

Lichaa faces a nervous wait in the results of scans that could rule him out for most of the season.

Raiders stars Austin, Sezer to miss six weeks

Aidan Sezer enjoyed a stellar debut for the Raiders but copped a nasty facial injury. ( AAP: Lukas Coch )

The Canberra Raiders will be without their new star halves for at least a month, with Austin and Sezer to be sidelined with injuries.

The Raiders on Monday confirmed the pair will miss between four to six weeks of NRL action following a brutal round-one win over Penrith on Saturday.

Half-back Sezer will have surgery this week to repair a fractured eye socket - an injury he sustained while scoring two tries on debut for the club in the 30-22 victory.

Dally M five-eighth of the year Austin, who spent the entire off-season recovering from major shoulder surgery last September, has escaped the knife but faces intense rehabilitation on his knee for medial ligament damage.

The playmaking duo had been touted as one of the league's best this season, with the potential to guide the Raiders to their first finals since 2012.

"It's very disappointing," winger Jordan Rapana said.

"I guess the positive to that is we've got a lot of depth there, so I'm sure Stick (coach Ricky Stuart) will have no trouble in playing our back-up halves.

Sam Williams is likely to slide in at half-back for this Saturday's clash with the Sydney Roosters at Canberra Stadium after recovering from a virus that struck him on the eve of the Panthers' game.

Stuart has a number of options for the number six position, with full-back Jack Wighton and boom rookie Lachlan Croker both contenders.

AAP/ABC