GREATER Western Sydney has suffered another blow to its key defensive stocks with news that Caleb Marchbank is set for another substantial stint on the sidelines.

Marchbank rolled his ankle in the Giants' round two win over Geelong at Manuka oval, and re-injured himself after returning ahead of schedule in the reserves at Spotless Stadium on Saturday.

The athletic defender hobbled from the ground in the second half and received treatment from GWS medical staff, and although he returned to the field shortly after, was limping significantly.

GWS will take no risks with Marchbank and he will miss the next five to seven weeks.

With co-captain Phil Davis (hamstring) and Aidan Corr (ankle) also injured, the 19-year-old's absence places more pressure on Joel Patfull and Tim Mohr, who returned for his first senior game in almost two years after two knee reconstructions against Gold Coast last week, to fill the key posts against the Western Bulldogs this Sunday.

The Giants' cause has been helped by the suspension of Jack Redpath, with former Giant Tom Boyd (shoulder) also missing from the Bulldogs' side.

Young GWS midfielder Jake Barrett, one of last week's emergencies, will miss the next two to three matches after straining a hip flexor, but in better news, important midfielder Toby Greene will return to face the Dogs after missing last week's win over the Suns due to soreness.