Tariq Sims' first-half hat-trick set St George Illawarra Dragons on their way to a 48-18 win over Brisbane Broncos in Sunday's NRL elimination final.

The Dragons arrived at Suncorp Stadium facing a tough task against a Broncos outfit that had defeated top-four sides Sydney Roosters and South Sydney Rabbitohs in the closing weeks of the regular season.

But it is the visitors who advance to next week's semi-final meeting with the Rabbitohs, who were edged out by the odd point in 57 against Melbourne Storm on Friday.

The Dragons' win came at a cost, however, as James Graham left the field for a head injury assessment and did not return, while Jack de Belin (foot) and Gareth Widdop, who looked to have dislocated his right shoulder, are also injury concerns for head coach Paul McGregor.

Brisbane began strongly and scored the first try through David Fifita following Kodi Nikorima's break. That gave the hosts a 10-2 lead but the Dragons came roaring back, running in 26 unanswered points before half-time.

Sims span away from his marker for his opener, Leeson Ah Mau crashed under the posts to put the Dragons in front and Widdop's perfectly timed pass sent Sims in for his second.

And the former Broncos Under-20 player, going up against younger brother Korbin, ensured the family bragging rights would be his with another spin move to complete his hat-trick.

The Dragons continued to target the right side of the Broncos' defence, Timoteo Lafai proving too strong for James Roberts early in the second period for a fifth score.

Brisbane briefly threatened a comeback via quickfire tries from Darius Boyd and Nikorima - Widdop injuring his shoulder in the lead-up to the latter - but the Dragons ensured it would be they who progressed as Luciano Leilua and Matthew Dufty capped off an impressive performance.