Dragons rule out Merrin for two weeks

St George Illawarra lock Trent Merrin will be sidelined for two weeks to recover from a shoulder injury suffered in State of Origin III last week.

St George Illawarra NRL lock Trent Merrin has been sidelined with a shoulder injury. (AAP)

St George Illawarra will be without Trent Merrin for their next two NRL games as the big forward recovers from a shoulder injury.

The Dragons confirmed the prognosis on Monday after scans revealed the extent of the damage suffered while playing for NSW in State of Origin III last week.

The club's performance director Andrew Gray said Merrin was working hard on his rehabilitation program and expected him to be fit for selection for their round-21 fixture against defending premiers Sydney Roosters on August 2.

While Merrin mightn't be available for next Monday's clash with Manly at Kogarah, the Dragons could welcome back fellow Blues representative Brett Morris.

The winger is hoping to be fit for the match after dislocating his shoulder in Origin I in May.