Knights co-captain Jamie Buhrer has been cleared of a ruptured ACL after scans came back negative, instead revealing a torn meniscus.
The utility hurt his knee on Saturday during his side's 16-18 loss to the Roosters, limping off the field in pain.
Scans revealed the 28-year old suffered damaged ligaments and which required surgery on Tuesday night, forcing him to miss six to eight weeks.
In other news, centre Nathan Ross will not take the field this week, with his groin injury taking longer to heal than expected.
Ross is hopeful of returning for Newcastle in next week's clash with the Bulldogs.
Finally, prop Daniel Saifiti is recovering well from the Lisfranc foot injury he sustained in the Knights' Round 13 win against the Eels.
"Halfway through the first half, my foot got caught in an awkward position," Saifiti told newcastleknights.com.au.
"There was a bit of a strain through one of the ligaments. Luckily I don't need surgery.
"Fingers crossed for a quick recovery and back in four or five weeks."
Knights injury list and expected return dates:
Tautau Moga (ACL, Season)
Jacob Saifiti (Shoulder, Round 24)
Jamie Buhrer (Knee, Round 19-21)
Mitchell Pearce (Pectoral, Round 18-19)
Daniel Saifiti (Foot, Round 18-20)
Nathan Ross (Groin, Round 16-18)