Cobblers conceded twice in the final five minutes as they let a fourth successive victory slip agonisingly through their fingers when hauled back to a 2-2 draw by Oldham Athletic.
The visitors were on course for another three points from the moment of Matty Warburton's sixth-minute opener and victory looked certain when Andy Williams superbly curled home a second goal late on.
But, for the third time this season, Town surrendered a two-goal advantage as Scott Wilson pulled one goal back and then Jonny Smith's deflected cross in the final minute of normal time somehow found its way into the net
It was an agonising and cruel finish for the Cobblers, who would have moved into the play-off positions and within four points of top spot had they managed to hold on at a rain-soaked Boundary Park. As it is, they drop to ninth and are left to rue another missed opportunity.
Before kick-off, manager Keith Curle lost Shaun McWilliams (illness) and Scott Pollock (injured) so in came Chris Lines and Warburton, who started behind Harry Smith in attack.
Warburton was at the centre of the action during a sharp start from the visitors and drew the first save of the afternoon when Zeus De La Paz parried his low effort around the post two minutes in.
However, Warburton was presented with a far better chance just six minutes later and this time he made no mistake. Oldham only half cleared a corner, the ball was fizzed back in by Lines and there was Warburton, perfectly-placed, to score at the second time of asking.
That was just reward for an assured and confident start by the visitors, although it appeared to jolt Oldham into life and they responded through Filipe Morais' header and then Jonny Smith, who rippled the side-netting.
Chris McCann saw a penalty appeal waved away but Cobblers had surrendered the early initiative and Oldham were now coming on strong and probed for an equaliser.
That said, clear-cut chances were not easy to come by and Morais was forced to into trying his luck from range on two occasions, first repelled by David Cornell and then curling a yard or two over.
Up the other end, attacks had become increasingly rare but Warburton let slip a great opening to double his and Town's tally in the final minute of the half. Scott Wharton headed a deep free-kick into the midfielder's path but he could only shoot against the crossbar.
It was more of the same after half-time with Oldham again seeing more of the ball and pushing for a way back into the game but Cobblers' stubborn defence went past the 400-minute mark without conceding a goal.
The home side were repeated met by firm resistance as attacking situations regularly petered out and Cornell remained largely untested.
Cobblers also weren't without their moments in attack and with eight minutes to go they should have had the points wrapped up. Lines showed good vision to pick out Williams, who still had plenty to do as he brilliantly curled into the top corner with his left foot.
However, somehow two points slipped away from Town in a dramatic finish. First substitute Wilson set up a tense finish with a well-taken goal four minutes from time and then Smith's cross deceived Cornell and floated into the net.
Oldham had all the momentum in six minutes of added time and Town were forced into some desperate measures to hold on for a point, something which they just about achieved - though it will feel like two lost.
Oldham: De La Paz, Iacovitti, Stott, Missilou (Emmerson 83), Azankpo (Wilson 67), McCann, Smith, Wheater (c), Eagles, Hamer, Morais (Maouche 79)
Subs not used: Woods, Fage, Sylla, Egert,
Cobblers: Cornell, Goode (c), Wharton, Turnbull, McCormack (Harriman 80), Lines, Warburton, Hoskins, Anderson (Williams 58), Adams, Smith (Oliver 67)
Subs not used: Fisher, Hall-Johnson, Kaja, Waters
Referee: Peter Wright