Newcastle Knights backrower Sione Mata'utia is facing up to six weeks on the sideline after suffering high grade knee medial ligament damage during Saturday's trial loss to St George Illawarra at Maitland Sportsground.
Mata'utia's knee gave way during the third quarter of the 38-12 defeat and he had to be assisted off the field before limping back to the change rooms.
Fears of a significant injury were realised on Tuesday after scans confirmed serious medial damage. He now faces a six week recovery period which could potentially keep him out of the first three rounds of the premiership.
But the Knights medical staff are optimistic he may be back on the field earlier with Mata'utia a "quick healer".
The injury is a real blow for Mata'utia, who was almost certain of starting the club's season-opening premiership clash against the Warriors in less than three weeks in the backrow.
Coach Adam O'Brien may now look to veteran Aidan Guerra to fill the backrow void or switch lock Mitch Barnett back to the right edge, the position he filled for the majority of last season.
