Sea Eagles fullback Tom Trbojevic.

Manly are expected to be without superstar fullback Tom Trbojevic for at least the opening round of the season after a hamstring injury in Saturday night's trial against Cronulla.

Scans have confirmed a hamstring tear for the Manly No.1, who now faces a four to six week recovery period.

Trbojevic picked up the injury in the 28-22 loss at Shark Park on Saturday night.

The NSW and Australian representative is highly unlikely to play in the club's opening game of the season against the Wests Tigers at Leichhardt Oval on March 16.

However, Manly are hopeful he could return in time for the club's round two clash against premiers the Sydney Roosters in a mouth-watering showdown against Kangaroos fullback James Tedesco.

Manly will play one more trial against the Sydney Roosters in Gosford next Saturday night to round out their pre-season preparations.