Souths coach Ben Hornby confirmed on Wednesday Walker would overcome a calf strain to play, while there is still no call on if Latrell Mitchell will play again this year after his foot injury.
The Rabbitohs' clash with Melbourne on Thursday night kicks off a month of must-win football for three teams, who could each have any faint finals hopes extinguished this weekend.
Rabbitohs coach Ben Hornby assumes his team can't make the finals. (Dan Himbrechts/AAP PHOTOS)
In 15th place, Souths need the biggest miracle of all to make the finals, but are still mathematically a chance after recording 12 losses in the first 22 rounds.
After Melbourne, the Rabbitohs have winnable games against Wests Tigers and Newcastle before finishing against Penrith and the Sydney Roosters.
"I don't know where the mathematics are at, but I am assuming we can't make it," Hornby said.
"I'm not looking forward and thinking about next week, I am looking forward to this week.Â
"We just take each game as it comes. Each game is going to be a bigger challenge for us, and a great opportunity for us to go up against great players."
Brisbane fit into the same category, with last year's grand finalists also clinging to a scant mathematical chance of making the top eight.
Wins in their final four games, along with the bye, would leave the Broncos hanging on other results.
The Broncos would also need everything to go their way to make the finals. (Jason O'BRIEN/AAP PHOTOS)
And the Warriors' predicament looks equally dire, after being last year's fairytale team of the finals before slumping to 13th on the ladder this season.
Realistically, those mathematical possibilities could end this weekend with each of Souths, Brisbane and the Warriors facing higher-ranked teams in round 23.
The trio of teams are not alone in potentially having their season decided in coming days.
Gold Coast are the form side of the bottom half of the ladder, but would slip into the mathematical-chance category with another loss.
They must first get through Cronulla on Friday night, and while they have the Sydney Roosters in a fortnight they will likely face a depleted Penrith in the last rounds.
Newcastle's last month is arguably the easiest of any team hoping for a miracle, but they too risk having their season over if upset by Wests Tigers on Sunday.
That could effectively leave the NRL with a 10-horse race by the end of the weekend, with the Dolphins and Canberra attempting to keep pace with the bottom of the top eight.
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