Out-of-sorts in attack and needlessly ill-disciplined in defence, the Tigers watched their captain Koroisau limp off the field with 23 minutes to play.
The club were hopeful the issue was only a back cork, but if it was to be anything more serious it could have State of Origin implications for NSW.
In front of a sold-out crowd, Koroisau looked to be the only Tiger offering the team any spark in attack before his injury on Saturday night.
They had enough good ball in the first half to trouble the Broncos, but only threatened to crack them once when Koroisau crossed but was ruled to have dropped the ball.
By the time the hosts did find points through a late Charlie Staines double, the game was gone.
In contrast, Brisbane regularly provided moments of brilliance.
Jock Madden scored a double but finished the night with a pectoral injury, while Reece Walsh also bagged two tries and was at his electric best before struggling with leg cramps late.
Payne Haas was powerful on return from a knee injury and scored one try with an unstoppable charge, while Brisbane capitalised on needless Tigers penalties.
Deine Mariner's first try was a sign of things to come, a superhuman one-handed put down within centimetres of the sideline in the fifth minute.
And after Samuela Fainu was sin-binned for tackling Corey Oates as the Bronco ran back to take a 20-metre tap, Madden scored in the next set from an Adam Reynolds banana kick.
Walsh's four-pointer on halftime was another thing of beauty.
Reece Walsh (centre) scored two tries for the Broncos. (Brett Costello/AAP PHOTOS)
With seconds on the clock, Reynolds chipped across field for Mariner who cut back inside and found a flying Walsh who made it 16-0 at the break.
Another Brisbane try came in the second half when Brendan Piakura put on a brilliant offload for Madden, again after Tiger Fonua Pole was penalised for a push.
And Walsh scored another later in the second half when turned back inside by Reynolds, as he finished with 201 metres to go with his two four-pointers.
Brisbane expect to have Ezra Mam (finger) and Selwyn Cobbo (shoulder) back on Friday against the Sydney Roosters, and are clearly a team building for a shot at redemption this year.
The Tigers, meanwhile, are spiralling and have now lost 10 straight at Campbelltown since June 2020.
With two wins in their first three games of this year, they looked like they had a new lease on life under Benji Marshall.
But the joint-venture are now returning to the Tigers of old, sitting 13th on the ladder after four straight defeats.
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