Kettering Town won the Maunsell Cup final by beating the Cobblers 5-3 on penalties following a 1-1 draw at Wellingborough's rain-soaked Dog & Ducks Stadium on Saturday.
Dean Bowditch fired Northampton ahead 18 minutes into a first-half the League One side dominated, but a flurry of missed chances would come back to haunt them.
Kettering, who play in the Southern League Premier Division, gave a good account of themselves after half-time having previously been outplayed. and a wonder strike from Michael Richens early in the second period was enough to force penalties.
Daniel Powell, Marc Richards and Yaser Kasim all scored their spot-kicks but Bowditch was denied by a fine save and that proved telling as Kettering took the honours.
Neither Aaron Pierre nor Matt Crooks featured on Saturday following their arrivals earlier in the week, as Justin Edinburgh tinkered with system by playing 3-5-2.
Ash Taylor, Regan Poole and Leon Barnett made up a three-man defence with George Smith and Aaron Phillips deployed as wing-backs and Kasim partnering Sam Foley in central midfield.
Dean Bowditch playing behind a front two of Billy Waters and Richards, and the Cobblers, whose starting line-up contained only three players from last season, settled smoothly into their new formation in a dominant start to Saturday's contest.
Barnett headed a corner over and Waters was twice denied before a rare Ketting attack ended with the ball in the net but an earlier foul on goalkeeper David Cornell ruled the goal out.
Town continued to make the most of the running, and in the 19th minute they had the lead. A neat move down the left culminated in Foley getting to the byline and cutting the ball back to Bowditch, who coolly sent Kettering's Paul White the wrong way to find the bottom corner.
With the two wing-backs enjoying plenty of freedom down either flank, Town maintained their control of both possession and chances, and they came close to adding a swift second on more than one occasion but Foley - three times in three minutes - and Ash Taylor were both thwarted.
Bowditch then fluffed his lines when presented with a golden opening to double his and Northampton's tally, dragging his shot wide, before White just about clung on to Phillips' fierce drive and followed that up by keeping out Waters from close-range as chances arrived in a flurry for the visitors.
The Cobblers were unable to extend their lead prior to half-time despite continuing to dominate, and they picked up from where they left off in the second-half with White at full stretch to save well from Richards' venomous free-kick.
Though Kettering did improve and come more into the game, their equaliser on 54 minutes was something of a bolt from the blue. Having picked up possession 40 yards from goal, Richens unleashed what seemed a speculative long-range effort which deceived Cornell and nestled into the bottom corner.
The Poppies had been second best up until that stage but the equaliser gave them the confidence to go at their League One opponents, and they should have gone ahead when Rene Howe hooked over from close-range.
In what was now a far more even and competitive affair, Town regained their composure and nearly re-took the lead themselves but neither Waters nor any of his team-mates could force the ball over the line from Brendan Moloney's low cross.
Moloney's arrival, in place of Phillips, had made a notable difference to the visitors as he lashed just wide from inside the box, but the best chance fell to Bowditch, who failed to hit the target with the goal gaping after a fumble from keeper White.
White made amends for that by excellently denying substitute Daniel Powell from an acute angle, and there was then some late worry for the Cobblers when Foley picked up some kind of leg injury and was forced off.
Northampton chased a late winner and Moloney almost found it but he was denied by the woodwork in the final minute, meaning it was left to a penalty shoot-out to decide the winner and Kettering scored all five spot-kicks to take victory.
Cobblers: Cornell, Phillips (Moloney 61), Barnett, A Taylor, Poole, Smith (Buchanan 61), Kasim, Foley (M Taylor 87), Waters (Powell 70), Bowditch, Richards
Subs not used: Goff, Lobjoit
Kettering: White, Bateman, Brighton, Mulligan, Langdon, Meikle, Miles, Hoenes, Hicks, O'Connor, Howe
Subs: Richens, Meakin, Baker, Boeland, Stohrer, Solkhon, Sundrie
Referee: Ian Rathbone