A George Burgess elbow strike has soured South Sydney's dramatic 24-18 win over Newcastle on Saturday.
Souths became just the second team to win after trailing at halftime this season, overcoming a two-point deficit at the break.
But it may come at a big cost.
Burgess could face time on the sideline after elbowing Knights forward Mitchell Barnett in the side of the head during the first half at McDonald Jones Stadium.
Burgess, who knocked a ball on in the first tackle from the kick-off for the second time in the game, lashed out at Barnett after the hit.
He was sin-binned as a result of the incident, and also placed on report, but coach Michael Maguire refused to comment on the strike after the match.
"That's a discipline area - we'll talk about internally," Maguire said.
"But it put us under a lot of pressure so we need to make sure that we're a lot better than that."
Rabbitohs' centre Hymel Hunt may also find himself in trouble after flooring Knights fullback Brendan Elliot with a high shot.
In further concerns for the Rabbitohs, halfback Adam Reynolds appeared to carry a right shoulder injury for most the match, just a week after returning from appendix surgery.
Reynolds said after the match he had suffered from whiplash and had striking pain down from his neck, but Maguire is confident it wasn't anything serious.
It didn't stop the Bunnies No.7 him setting-up the match-clinching try with a perfectly-timed lofted pass for winger Braidon Burns.
It gave Souths a 22-12 lead with just over 20 minutes remaining, and from there they added to their lead with a penalty goal before Knights winger Ken Sio scored a late consolation try.
Knights captain Trent Hodkinson was also sin-binned late in the game, after telling referee David Munro he had "just cost (Newcastle) the match" when Souths won a scrum against the feed.
It killed off the depleted Knights, who were already reduced to two on the bench through concussions and had Nathan Ross struggling with an ankle injury - prompting coach Nathan Brown to again call for an 18th player to be available for head knocks.
"We're not addressing the bigger problem," he said.
"There are injured players being forced to stay on the field because we don't have any players left."
Souths recovered to take a 10-0 lead after Alex Johnston and John Sutton each scored, but Burgess' brain explosion brought the Knights back into the match.
Newcastle scored twice while he was off the field, Hodkinson pivoting his way over in the ensuing set and Peter Mata'utia making the most of the numbers advantage when brother Sione put him through.