Southern Suburbs, Brighton and Burnside all remain unbeaten heading into Round 4 while Barossa and Onkaparinga enjoyed tight wins last weekend.
In the livestreamed match of the round, Souths weathered an early Port Adelaide storm to run out 57-0 victors at Riverside Oval.
An early red card reduced the Pirates to 14 men but the hosts defended grimly with Souths needing a 26th minute solo try from Isoa Ronavuso to break the deadlock.
Further tries to Tom Wigget and Sam Rowe put the Bulls up 19-0 at oranges before Port's tiring defence gave way with Tilly Bici bagging his third brace in as many weeks and Rowe completing his hat-trick after half time.
Meanwhile Burnside and Brighton enter this weekend's Premier Grade GF rematch in fine fettle after dominant displays in Round 3.
Piers Deignan scored a hat-trick in the Tigers' 76-7 win over Woodville while Burnside laid on 13 second-half tries to roll the Knights 93-12 at Womma Park.
Barossa's Joe Crouch proved the difference off the tee as the Rams edged Adelaide Uni 31-29 with Onkas rounding out the weekend in style, downing Old Colls 29-21 at Wilfred Taylor Reserve.
In the women's competition, Woodville remain the only unbeaten side following a 29-15 win over Burnside, who drop to second place, while Uni and Onkas kept a clean sheet against Barossa and Port respectively.
Brighton and Old Colls maintained their winning ways in Reserve Grade with the Tigers Gold also holding top spot in Third Grade following a 40-point win over previously unbeaten North Torrens.
