Kotoni Staggs' hat-trick inspired Brisbane Broncos to a 22-18 triumph over South Sydney Rabbitohs.

Souths fell to a double-digit deficit in the first half as both Staggs and Anthony Milford powered in on the right, but the visitors fought back prior to the break.

Scores from Campbell Graham, who had earlier lost the ball when going over the line, and Cody Walker drew them level before Adam Reynolds' two-pointer meant Souths led 12-10 at half-time.

However, Staggs' devastating finishing proved the difference in the second half as he crossed twice more, rendering Alex Johnston's late score a mere consolation in a contest staged behind closed doors due to the coronavirus outbreak.

It was another off night for Latrell Mitchell, the Rabbitohs' prized close-season addition from Sydney Roosters, with the NRL's top points-scorer of the previous two years yet to register a point after two games for Souths.

Elsewhere, Penrith Panthers came from 10 points down with 12 minutes to play to beat St George Illawarra Dragons 32-28 in a high-scoring thriller.

There were five tries apiece in Sydney and Nathan Cleary's 16-point haul proved crucial as the Panthers, who stunned Sydney Roosters in their first game, made it two wins from two.

The Dragons fell 12-0 down but a 90-metre break from Matthew Dufty for one of his two tries got them into a game they soon took control of.

Viliame Kikau's 68th-minute score gave Penrith hope, though, and after Stephen Crichton took a return pass from Liam Martin to finish a move he started, Cleary's boot did the rest.