Maitland came from behind then held on with desperate defence to defeat Hamilton 2-1 and secure a first FFA Cup round of 32 berth at Cooks Square Park on Tuesday night.
Hamilton were sharp early and scored on three minutes when Marcus Duncan caused a turnover before finding Scott Pettit, whose cross was knocked into goals by keeper Matt Trott.
Maitland worked their way into the game and grabbed a deserved equaliser in the 48th minute when Olympic keeper Tyler Warren spilled a Liam Thornton corner.
The Magpies were ahead in the 73rd minute when Joel Wood scored from the spot after Rhys Cooper bundled over Carl Thornton.
Hamilton, also chasing a first appearance in the nationwide knockout's main draw, pushed hard for an equaliser late.
Substitute Jed Hornery missed two chances in the final 10 minutes while Jarryd Sutherland forced a full-stretch save from Trott in the 86th minute.
The Magpies had their chances on the counterattack but Wood was wide and Grant Brown was stopped by a great Warren save.
Edgeworth and Valentine clash on Wednesday night at Speers Point to decide the other Northern NSW representative in the main draw.
Maitland struggled with the pace of Kent Harrison and Cooper in transition early but they held on.
Trott smothered a shot from Harrison in the seventh minute and a deflected shot from Cooper in the eighth bounced off the crossbar twice.
Trott dived to deny a Reece Papas free kick in the 15th minute and Duncan was into the side-netting with the follow-up. Papas tested Trott again in the 27th minute but he knocked the strike wide.
The hosts went close in the 21st when Wood was just wide after a soft back-pass from Duncan opened the door. Wood forced saves from Warren in the 31st and 40th minutes and Sutherland saved Hamilton with a goalline header in 37th.
Maitland had shouts for a penalty for handball denied in the 55th and Warren scrambled to stop a one-on-one shot from Wood in the 65th.