Richie Kennar will have scans on an injured ankle with initial fears the South Sydney winger could miss the remainder of the season.
Kennar left the field late in the second half following a Broncos try and immediately went up the tunnel in discomfort.
Rabbitohs coach Anthony Seibold confirmed post-game the injury was being treated as a worse case scenario.
"It looks pretty serious from what the medical staff tell me, potentially season ending," Seibold said.
"The initial discussion with the performance staff straight after the game wasn't positive. I understand it's a similar injury to Jordan McLean from the Cowboys."
It added to a disappointing result for the Bunnies who let a 12-6 half-time lead slip with the Broncos charging home in the second half on the back of a 60 per cent possession rate.
The Rabbitohs had further motivation on the back of Greg Inglis' 250th match and Tom Burgess' 100th appearance in the NRL.
"We'll view it, dump it and jump into the Knights," Seibold said.
"We were a bit off in regards to attention to detail. That was the most disappointing.
"Broncos teams tend to hang tough and work hard for each other. We had an opportunity to score another try there, we just didn't get the job done.
"We felt confident at half-time but weren't good enough.
"We're disappointed we didn't play our brand of footy. We spoke about the errors. It's important for Greg tonight and Tom. To not get the result was disappointing."
Inglis said the milestone was not a distraction and was focused on the result more than the occasion.
The 31-year-old told reporters earlier in the week he contemplated retirement during a long road back from an ACL injury last season.
"I've been blessed to be in this game for a very long time," Inglis said.
"I'm not worried about that at the moment, I'm worried about our team performance. I'll go home and celebrate the milestone, but in terms of the team effort and myself included, it wasn't up to standard.
"We lost it in the first 15 minutes (after half-time). Every Broncos team in the past has hung in there and that hasn't changed. We felt we've improved and showed signs of our potential. I think the last five weeks we've been relatively happy."
The Rabbitohs were coming off a five-day turnaround after their 42-22 victory over the Raiders on the Central Coast in round seven, but Siebold said the limited preparation was no excuse for their flat performance.
"I don't think it has any impact at all," he said.
"What hurt us is they had 60 per cent of the ball. We talk about building pressure and effort. And I didn't see that tonight."