Cody Walker will miss South Sydney's crucial clash against Cronulla with a calf niggle.
The halfback suffered his injury during last Sunday's loss to Canberra and pulled up sore attempting to train for the first time this week at the captain's run.
"He won't play," interim coach Ben Hornby said on Friday.
"He's just not right, he doesn't feel like he can get through the game so there's no point putting him in that situation.
"We'll just give it another week and go from there."
Already four points adrift of the NRL's top eight and with an inferior for-and-against, the 15th-placed Rabbitohs' already slim finals hopes will virtually be over with a loss on Saturday.
In Walker's absence, Souths will rely on rookie Dion Teaupa to steer the ship from halfback in only his fourth top-grade game.
The Rabbitohs are hopeful Walker will return to host ladder-leading Melbourne next Thursday night.
He joins try-scoring wizard Alex Johnston and star fullback Latrell Mitchell as recent casualties in a horror season of injuries at the club.
Campbell Graham, Tevita Tatola, Isaiah Tass and Jai Arrow are among other Bunnies nursing season-ending issues, though the side does welcome captain Cam Murray back from suspension for the Cronulla trip.
"It's been a tough year on the injury front, I thought we'd stopped it for a while but it seems to have come back again," Hornby said.
"They're the cards we've been dealt, we've still got a side that's good enough to go out there and be competitive."
The talismanic Mitchell's season may not yet be over as he nurses the foot injury that robbed him of a NSW berth in State of Origin III.
The 27-year-old has three more weeks in a moon boot, though, and Hornby warns he may require more time on the sidelines after that.
"There's going to be a build-up period there to see where it's at," he said.
"At the moment, we've got another scan and the boot for three weeks and then we go from there."
