WOLLONGONG, AUSTRALIA - JULY 14: Nick Cotric of the Raiders walks from the field after being sent off for a tackle on Timoteo Lafai of the Dragons during the round 17 NRL match between the St George Illawarra Dragons and the Canberra Raiders at WIN Stadium on July 14, 2019 in Wollongong, Australia. (Photo by Mark Metcalfe/Getty Images)

The Canberra Raiders will now be without their entire full-strength back three for this weekend's clash against the Newcastle Knights after losing Nick Cotric to injury.

The club registered their first win of the season on Sunday afternoon, defeating Cronulla 24-20 in front of a packed GIO Stadium filled with fans still riding the high of watching Corey Horsburgh crash over for a rare double.

However, they were forced to do so after losing former Kangaroo and New South Wales' back Nick Cotric, who suffered a hamstring injury during the week at training, handing James Schiller a game day call-up.

While initially thought to be minor, scans have revealed the full extent of Cotric's damage, with the winger set to miss at least a month of football for the Green Machine.

The club confirmed the news on Monday.

"Nick Cotric is also facing 4-6 weeks on the sideline after injuring his hamstring at training late last week," the club said via their rehab report.

Xavier Savage is still at least a month away, while Jordan Rapana is unavailable this weekend as he serves the final game of his suspension dating back to Round 1.

While it's an obvious exodus of experience in the backline, the casualty ward has allowed youngsters like Harley Smith-Shields and Albert Hopoate to stake their claim for a permanent position, especially with Rapana off-contract at season's end.

The side will travel to Newcastle to face the Knights on Sunday afternoon, who are struggling with a full casualty ward of their own. In a further blow to the Knights, Canberra are expected to name Josh Papalii for the first time this season.