The Cobblers’ poor run of form continued as they were beaten 2-1 by Carlisle United at Brunton Park.
The Cumbrians had lost their previous three games going into the final fixture before Christmas but banked the points through goals from Troy Archibald-Henville and Brad Potts.
Marc Richards had restored parity with his 10th goal of the season from the penalty spot after Evan Horwood was fouled in first-half stoppage time.
But Potts’ goal midway through the second half settled it and although Northampton had a lot of the ball, they lacked the penetration to get back in the game.
Chris Wilder made four changes to his team but despite the alterations, it was Carlisle who seized the attacking initiative in the game, Danny Grainger drawing a blocked save from Matt Duke with a cracker of a shot and David Amoo driving the rebound wide of the target.
Ollie Banks got a sweet connection on a cross-field pass from Joel Byrom which fortunately evaded the covering defender, Dan Hanford tipping the shot away for a corner kick.
Nothing came of that set play and on 16 minutes Carlisle took the lead from one of their own, Archibald-Henville glancing in a header from Kyle Dempsey’s corner from the left wing.
The next set-piece the home side had was again aimed towards the centre-back, who escaped the attentions of Zander Diamond to steer a headed effort narrowly over the bar.
The Cobblers were firmly on the back foot at that point but Darren Carter drew a good save from Hanford, high to his left, with a firmly-struck right-footed shot from 20 yards.
Every member of the away contingent - all players and coaching staff - wanted a penalty when Byrom’s shot at the second attempt was blocked on the line by Danny Grainger but the referee waved away the appeals.
They were handed a lifeline when David Amoo clumsily brought down Evan Horwood in the box for a clear penalty which was buried by Richards.
Having not given a spot-kick moments earlier, there was a feeling that the referee had that incident in his mind but it was a clear foul by Amoo and a completely unnecessary one too.
It gave the Cobblers a foothold in the game and they started the second half well, with Ivan Toney displaying an impudent confidence to attempt a left-footed shot on the turn from fully 25 yards.
Toney then won and took a free-kick on the edge of the box, firing low to Hanford’s left before former Cobbler Derek Asamoah struck a shot just wide of Duke’s right-hand post after a counter-attack.
The home side regained the lead on the hour mark, Potts converting Amoo’s right-wing cross at the front post after excellent hold-up play by Asamoah.
Tom Anderson cleared off his own goal-line after Hanford had blocked a Toney shot at the back post as the Cobblers sought a route back into the game.
Wilder made a double substitution with 25 minutes to play, introducing Chris Hackett and Kaid Mohamed as wide midfielders in place of Ollie Banks and Joel Byrom.
Hackett’s best piece of play came when he was set free down the right and guided a cross into Toney, whose header was well held by the goalkeeper.
Duke made a superb save from a Mark Beck header at a long throw as Carlisle looked for a win-sealing third goal.
They did not need it.
Carlisle: Handford; Brown, Anderson, Archibald, Grainger; Amoo, Sweeney, Dempsey, Potts; Beck, Asamoah
Subs: Hammell (for Asamoah 79), Meppen-Walter (for Amoo 90)
Not used: Robson, Kearns, Thirlwell, Brough, Eccles
Cobblers: Duke; Tozer, Diamond, Langmead, Horwood; Banks, Murdoch, Carter, Byrom; Toney, Richards
Subs: Hackett (for Banks 65), Mohamed (for Byrom 65), D’Ath (for Tozer 77)
Not used: Snedker, Collins, Robertson, Alfei
Away fans: 255