GWS stalwart Stephen Coniglio will join teammate Brent Daniels on the Gather Round sidelines.
Coniglio has been ruled out of Sunday's clash against St Kilda at Norwood Oval in Adelaide.
"Cogs' glute, we expected him to get through training fine but he didn't," Giants coach Adam Kingsley told reporters on Friday.
"So it's a bit disappointing but we move on pretty quickly.
"He didn't report it at training, he woke up after the main training session last week with soreness.
"He tried to get moving and couldn't get moving at captain's run so we don't know how it happened.
"I expected him to play this week so this means nothing: I expect him to be right for next week but I really don't know."
Coniglio joins Brent Daniels on the sidelines with the influential forward straining an abdominal muscle.
"It's a really weird one, I have never seen it before, it's apparently a muscle that 20 per cent of the population don't have," Kingsley said.
Kingsley said Harvey Thomas and Toby McMullin were in the frame as replacements for a crunch game between two clubs with a three-one win-loss record.
