Former Cobblers loanee Danny East returned to haunt his club with the winning goal in a costly home defeat to Portsmouth.
East scored after four minutes and although Northampton fought hard to find a way back into the game, their lack of a goalscorer cost them dearly.
It is a loss that is especially hard to take as the other struggling sides in league two all lost, meaning it’s still ‘as you were’ but with another round of fixtures consumed.
The home side took to the field in front of a loud home support and knowing Bristol Rovers had been beaten by Rochdale in the day’s lunchtime kick-off.
But it was the visitors, whose League safety had been secured by that result, who took an early lead.
Gregor Robertson conceded a free-kick high on the home side’s left wing which was hooked into the box for former Sixfields loanee East to divert over Matt Duke with just four minutes played.
The response was a decent one and should have generated an equaliser when space was created for an Evan Horwood cross down the left wing.
The delivery was inch perfect to the back post but Emile Sinclair completely failed to make any sort of contact on what should have been a headed tap-in.
John Marquis then forced Trevor Carson into a good save at his front post after turning inside full-back Danny Alfei in a tight area.
Darren Carter did likewise after bursting through from central midfield in the final minute of the first half, his follow-up shot then being blocked by a covering defender.
Sinclair could not have been kept on after his error and was replaced at half-time by Ivan Toney, who came close to an equaliser when he struck Chris Hackett’s cross from the touchline into the ground and over the bar.
Sonny Bradley sold his goalkeeper short with a headed back pass that Marquis cut off only for Carson to break from his line and block the shot.
The game should have been put to bed when Jed Wallace arrived at the end of a counter-attack after a Northampton corner only for Duke to race from his line and block the effort.
Kelvin Langmead, who played the final 10 minutes as an emergency centre-forward, had the best chance late in the game when a corner came all the way through to him 15 yards from goal.
But a defender slid in to block the effort and the resulting corner led to nothing.
Cobblers: Duke, Doumbe, Tozer, Robertson, McSweeney, Carter, Ravenhill, Horwood, Hackett, Sinclair, Marquis
Subs: Toney (for Sinclair 46), Morris (for McSweeney 46), Langmead (for Ravenhill 80)
Not used: Snedker, Deegan, Connell, Moyo
Portsmouth: Carson, Alfei, Devera, Bradley, Shorey, East, Wallace, Ertl, Fogden, Jervis, Ageymang
Subs: Hollands (for Jervis 54), Drennan (for Ageymang 64), Holmes (for East 78)
Not used: Smith, N’Gala, Webster, McCabe
Away fans: 1,359