Raunds Town will take on JK Blisworth in the final of the NFA Les Underwood Junior Cup later this season.
The Shopmates avenged last season’s semi-final defeat at Peterborough & District League Premier Division side Netherton United as they held their nerve in a penalty shoot-out.
James Le Masurier’s United Counties League Division One side looked to be heading through in normal time after Karl King gave them the lead with 15 minutes remaining.
But Netherton levelled on 88 minutes and that led to a shoot-out.
And Raunds goalkeeper Chris Jones was the hero with two penalty saves as the Shopmates triumphed 3-1 on spot-kicks to book their place in the Sixfields showpiece.
Rothwell Corinthians are now without a win in nine United Counties League Premier Division matches after they were held to a 1-1 draw by lowly Harrowby United at Sergeants Lawn.
Corinthians took the lead on 65 minutes thanks to a Jordan Henson penalty but the visitors levelled five minutes later.
The local derby between Wellingborough Town and Desborough Town was postponed due to a waterlogged pitch.
Whitworth moved to within two points of the promotion places in Division One after the crushed Blackstones 6-0 at the Victoria Mill Ground.
The Flourmen sit in fifth place in the table but are just two points behind second-placed Buckingham Town with three games in hand.
Thrapston Town enjoyed a fine away day as they secured a 4-2 success at Lutterworth Athletic but Rushden & Higham United slipped to a 2-1 defeat at Long Buckby after Steve Ainge had given them the lead in the first half.
Elsewhere, it was another tough day for strugglers Stewarts & Lloyds and Burton Park Wanderers.
The Foundrymen went down 4-1 at Melton Town while Wanderers were beaten 3-1 at Oakham United.