South Sydney are likely to face a sanction from the NRL due to the debut of forward Trent Peoples in Thursday night's clash with the Broncos.
Peoples played 64 minutes in his NRL debut, with the Bunnies having called on the Campbelltown product after a string of second rowers were ruled out of the match with injury.
The 23-year-old impressed in his maiden senior appearance, recording 24 tackles and 110 running metres.
In a turn of events, Peoples had not been cleared to play by the NRL for the Round 9 match, according to The Daily Telegraph.
Peoples is listed as a train and trial player in Jason Demetriou's squad, with the NRL having granted an exemption for the Souths player to be listed as 18th man last week as part of a game-by-game exemption basis.
A "paperwork blunder" is understood to have seen Peoples feature in the 12-32 loss to the Broncos illegally, having not gained clearance from the NRL's salary cap auditors.
"We’re aware South Sydney used a player on Thursday night who had not yet been approved by the NRL," an NRL spokesperson told News Corp.
"The Salary Cap Department is looking into why this happened and will finalise its investigation shortly."
Should the Rabbitohs have won the match, the NRL are likely to have deducted two premiership points from their season tally.
The club are still likely to face a significant fine from the league.
Peoples is still likely to line up for the Rabbitohs in their Magic Round clash with the Warriors in Brisbane next week as South Sydney chase their fifth win of the season.