Still far from their best on Saturday night, the home side completed at only 59 per cent in the first half before showing signs of improvement to come from 6-4 down and win.
The victory kept Cronulla in fourth spot on the ladder, and marked only their third victory in nine matches after exploding out of the blocks with a 9-1 start to the year.
It also killed off any slim hopes the Rabbitohs had of reaching the finals, on a night where they were forced to play without any of their first-choice backline.
Even still, Cronulla's victory was soured late with Trindall leaving the field and heading straight up the tunnel, after experiencing hamstring tightness in the second half.
The Sharks are already without Nicho Hynes until the eve of the finals after a serious ankle injury, and now face the prospect of another potential change in the halves.
If Trindall was to be sidelined, one option would be for NSW Cup centre Mawene Hiroti to shift to No.6 and partner Daniel Atkinson.
Former Penrith reserve-grader Niwhai Puru would be another option to make his NRL debut next week against Gold Coast.
Talakai goes BANG 💥— NRL (@NRL) #NRLSharksSouths @telstra Moment of the Match pic.twitter.com/OFaBwW3JAHAugust 3, 2024
Saturday's win was desperately needed for the Sharks.
Before this weekend, Cronulla's record since Magic Round had replicated the Rabbitohs' from the same period last year during their record-breaking collapse.
Damien Cook had moments of promise at dummy-half, while Jai Gray was particularly dangerous for the visitors.
Still deputising for Latrell Mitchell, the Souths No.1 opened the scoring when he made the most of a Sam Stonestreet error by cutting through the defence from a scrum.
Cronulla hit back through Sione Katoa when they created space on the right, but were denied twice in the first half through an obstruction and Stonestreet bobble.
And while they took the lead after the break through Stonestreet, South Sydney felt aggrieved after being penalised in the previous set for a two-on-one strip while trying to deny a try.
Then, at last, the old Sharks showed some sign of returning.
After repelling 19 straight tackles on their own line, Siosifa Talakai was able to break the game open for Cronulla when he ran through Michael Chee Kam.
That put Kayal Iro into space, who found Trindall on his inside to score and make the game 14-6.
Iro then scored himself four minutes later when he chased down a Trindall grubberkick, putting the game beyond doubt.
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