GREATER Western Sydney has suffered a blow as the start of the season nears with three key players, including young gun Finn Callaghan, battling to be fit for the Opening Round blockbuster against Collingwood.

Harry Perryman and Isaac Cumming will almost certainly not play the March 9 encounter with the Pies after suffering hamstring and quad injuries respectively.

Both are expected to be fit for the Giants' second clash of the season, also at home to North Melbourne.

The prognosis on Callaghan, who has a shoulder problem, is less serious.

He will definitely be sidelined for the Giants upcoming practice matches against Sydney on February 22 and then Gold Coast seven days later with a view to ensuring he's ready for the Pies clash.

It's not guaranteed, however, that he'll be 100 per cent fit for the rematch of last year's preliminary final.

He suffered the shoulder injury in training on Monday but it is understood the 20-year-old was doing some light weights training at the club on Friday while his teammates participated in match simulation.

The injury is still a setback for GWS and the former No.3 draft pick, who had impressed across the pre-season and is earmarked to develop into the X-factor in the Giants midfield in season 2024.

The absence of Perryman and Cumming for the season opener may mean an AFL debut is handed to 19-year-old speedster Darcy Jones.

The first-round pick of the 2022 draft has recovered from an ACL injury suffered last year and has caught the eye above all others across the Giants pre-season with his pace and excitement.

It's understood he's worked his way into squad calculations for the start of the season.