St George Illawarra Dragons co-captain Ben Creagh is set for a spell on the sidelines after undergoing knee surgery on Wednesday.
The 31-year-old Creagh missed the Dragons' 14-12 NRL win over the Penrith Panthers on Sunday due to the injury.
Dragons head of medical performance Tony Ayoub said it remained unclear just how long Creagh would be sidelined.
"Ben Creagh unfortunately had an issue with his knee last week which really stiffened up recently," he said.
"He has had some chronic knee issues for a long time and he battles through it and does quite well each week.
"Unfortunately, it just got the better of him towards the end of last week and we had to stand him down for the game against the Panthers.
"After seeing an orthopaedic surgeon on Tuesday we decided to give the joint a little bit of a clean-out and hopefully have him back sooner rather than later."
The win over the Panthers was the Dragons' second of the season and sees them sitting 12th in a congested ladder.
St George face last year's premiers North Queensland Cowboys in Townsville on Saturday.