A suspected broken jaw suffered by Adam Reynolds has soured South Sydney’s round one 42-10 NRL thumping of arch rivals Sydney Roosters.

A pectoral injury to John Sutton could be another big worry for Souths coach Michael Maguire.

With Reynolds pulling the strings, the Rabbitohs dominated their neighbours completely in the first half in humid conditions at Allianz Stadium on Sunday, racing out to a 26-0 halftime lead before 25,125 fans.

Cameron McInnes ducked over from dummy half in the sixth minute before Aaron Gray crossed out wide eight minutes later to give the visitors an early 10-0 advantage.

Reynolds, who easily outpointed his opposite Jackson Hastings, then laid on four-pointers with his boot for Paul Carter and Alex Johnston in the 17th and 23rd minutes.

Greg Inglis powered over to add further misery to the scoreline for the Roosters before the break.

From there the result was hardly in doubt.

But Reynolds’ injury suffered in the 58th minute in an innocuous-looking tackle on Kane Evans will be one of the main post-match talking points.

Early suggestions were the Souths No.7 could be sidelined anywhere from six weeks to the season.

A Kyle Turner try, before Reynolds’ injury blew the score out to 32-0 before the Roosters were finally on the scoreboard through Joe Burgess.

Englishman Burgess’ double on his NRL debut was one of few positives for a Roosters side missing Jared Waerea-Hargreaves, Boyd Cordner and Mitchell Pearce.