Matt Dufty in action for the Dragons NYC side in 2016.

Young Dragons fullback Matt Dufty has been sidelined for four to six weeks with a knee injury suffered at the Downer NRL Auckland Nines.

The 21-year-old speedster suffered the injury in St George Illawarra's match against the Manly Sea Eagles, with scans revealing a medial meniscus tear.

"After scans yesterday, it has revealed a medial meniscus tear," Dragons performance manager Nathan Pickworth said.

"He'll have an arthroscope today and that will be removed. The return-to-play time frame is around 4-6 weeks."

First-grade forwards Tyson Fizell (back) and Russell Packer (shoulder, hip) are expected to return from their injuries before Round 1 of the Telstra Premiership season.