Cody Walker will miss South Sydney's final game before the State of Origin teams are picked, in another blow to a NSW side bereft of halves options.
Walker suffered a low-grade calf strain in last week's loss to North Queensland, and on Thursday evening Souths ruled him out of the round-12 clash against Parramatta.
A club statement said Walker could recover in time for the Origin series opener on June 5 if selected in the Blues squad on Sunday night.
But it remains to be seen whether NSW coach Michael Maguire would risk bringing a crucial member of the spine into camp under an injury cloud.
Walker was man of the match on his return to the Origin arena in game three last year and had thrust himself into the selection conversation with solid recent form.
The 34-year-old has assumed the Rabbitohs captaincy since Cameron Murray suffered a hip injury in early May, and in a struggling Rabbitohs side he has been one of few consistent attacking threats.
His injury comes as fellow halves options Nathan Cleary, Mitch Moses and Adam Reynolds all prepare to watch Origin I from the casualty ward.
Queensland five-eighth Cameron Munster will miss the series with a groin issue.
In-form Cronulla halfback Nicho Hynes has been battling a calf issue this month, but is expected to be fit to enter Blues camp if selected.
Jarome Luai and Matt Burton are two other options to play in the halves as the Blues look to start the series with a win on home turf at Accor Stadium in Sydney.
In Walker's absence, Latrell Mitchell will assume the Rabbitohs captaincy on Saturday night for Indigenous Round.
The Rabbitohs expect Walker will return to face Gold Coast after the round-13 bye.
