North Queensland could be without skipper Jason Taumalolo for up to six weeks, with the bruising Tongan lock set to undergo knee surgery.
The Cowboys, who have failed to recapture the form which propelled them to last year's NRL preliminary final, say Taumalolo has been carrying a cartilage issue over the last month.
The 29-year-old will go under the knife later this week.
North Queensland have just two wins from their opening seven games and were already down on forwards with Luciano Leilua, James Tamou and Griffin Neame all sidelined.
Elsewhere, South Sydney will be without Keaon Koloamatangi for six to eight weeks after he picked up an ankle injury in their win over the Dolphins.
Souths say that Koloamatangi's stint on the sidelines could be extended if he has to undergo surgery.
It is a blow for the back-rower, who's been talked up as a contender to play in the NSW pack for the State of Origin opener against Queensland in Adelaide on May 31.
