The St George Illawarra Dragons have revealed they expect Tautau Moga to miss a month of action with a shoulder injury he sustained on Anzac Day.

Moga failed to play out the game against the Sydney Roosters on Anzac Day in its entirety, leaving the field after 66 minutes and with a hat-trick of tries to his name.

It was revealed immediately after the game that the belief was he had suffered an AC joint injury, and that has now been confirmed by the club as a Grade 2 problem.

"Tau [Tautau Moga] picked up an AC injury to his right shoulder scoring that try in the corner there," Dragons' head physio Davis Theobald said in a club medical update.

"It's a decent Grade 2. They usually turn around in that sort of four week timeframe. They are pretty individual, he is doing pretty well, so we just need the joint to stiffen up a bit and get his strength back and we will get him back out there."

Moga was replaced last weekend against the Canterbury Bulldogs in Wollongong by Max Feagai, while the return of Mikaele Ravalawa this weekend means he shifts into the centres.

Moga may not regain his place in the Dragons' side when he returns if they are at full strength, with the Feagai brothers vying for positions, and the fitness of Mikaele Ravalawa having returned - Moga originally replaced Ravalawa in the 17 when the Fijian went down injured.

Theobald said Ravalawa has recovered well to take on the Tigers this weekend, having originally been scheduled for a Round 11 return.

"He has hit everything that he needs to hit, has good training behind him and will be good to go this week," Theobald said.

The Dragons have also confirmed Jaydn Su'A will be fit to take the field tomorrow.

"He is doing really well. Strength and function is quite good, trained today and got through a decent amount of contact without issues, so pretty confident we will have him back this week," Theobald said.

Su'A and Ravalawa have both been named to play the Tigers with kick-off at 1:50pm (AEST) on Sunday in Brisbane.