GWS skipper Toby Greene will miss next week's Sydney Derby against the Swans with a quad injury, with no timeline on his return.
Greene made a lunge and felt his quad immediately, walking from the ground and being put on ice.
"He lunged for a tackle and just felt his quad," Giants coach Adam Kingsley said of Greene.
"I don't know any timelines on that at all, but we're on a six-day break into the Swans so – a big match – and he won't be available for that."
Greene's injury is emblematic of the club's inability to perform against the struggling sides, with Kingsley suggesting a "mental block" against the AFL's cellar dwellers.
The Giants succumbed to Essendon on Sunday by three points at Marvel Stadium. The loss puts finals in jeopardy, and continues a wretched run against teams below them - or around them- on the ladder.
As well as the Bombers, GWS has lost this season to West Coast, Carlton and St Kilda (twice).
"It must be some sort of mental block there that we haven't put our finger on yet and been able to solve," Kingsley said.
"That's all of us; we haven't managed to fix that.
"Until we do, we're not going to become the team that we want to become, and we've got plenty of work to do in that space.
"We've got sports psychologists at the club provided to us to be able to tap into.
"We've got the resources there; we've just got to do a better job, plain and simple."
Ironically, the Giants are much stronger against teams inside the top 10, knocking off Brisbane, Fremantle, Geelong and Hawthorn throughout the year.
They sit precariously outside the top 10 among multiple clubs vying for a Wildcard spot.
With the Swans ahead, GWS has a winnable three-game stretch against Port Adelaide, Gold Coast and West Coast, before finishing against the Crows.
