David Faupala's first goal for the Spireites wasn't enough as Chesterfield suffered a 3-1 defeat at Northampton Town.
Two first half goals from John-Joe O'Toole and a Marc Richards header gave the Cobbler's a three goal lead, leaving Faupala's effort too little to late.
Former Spireite Richards was the first to attempt to open the scoring at Sixfields, the forward had been slipped in by Keshi Anderson but his strike barely forced a save from Lloyd Allinson.
Northampton took the lead inside 15 minutes with just their second shot on goal, Hiram Boateng’s cross hit the chest of O’Toole and drifted past Allinson into his bottom corner.
In desperate search of a reaction, Dan Gardner attempted an audacious lob of Cobblers ‘keeper Adam Smith who had been caught outside his box, but it floated high and wide.
An acute ball from Dion Donohue landed with precision at the feet of Jon Nolan, the midfielder attempted to sneak it underneath Smith, but he was equal to it.
The Spireites had been controlling possession but creating very little, their frustrations showed as Dan Gardner sliced a strike at goal that instead fell to Sadiq El Fitouri in the far corner.
Still on the front foot, El Fitouri crossed to David Faupala but the on loan striker couldn't nod his effect past Smith.
Northampton piled more misery onto Chesterfield when O’Toole (41) claimed a second of the day, flicking a low ball from the left-wing across Allinson and into the bottom right corner.
Needing to freshen up the eleven at half-time, Gary Caldwell sent on Angel Martinez and Reece Mitchell in place of Gardner and Dan Jones.
The change sparked the Spireites into life as within minutes Smith was forced to deny the away side their way back into the game. Liam Grimshaw had been sent through by Nolan but the Cobblers ‘keeper clawed away the midfielder’s attempt to flick it around him.
Having almost halved the home side’s lead moments before, the Spireites then conceded a third, Marc Richards (47) heading a free kick past Allinson.
Chesterfield looked dead and buried but continued to fight, new signing Faupala (53) burst into the box and latched on to Donohue’s pass, before driving it low past Smith.
The Spireites were still clinging onto hope of a revival and El Fitouri ensured they remained in the battle, thwarting a Cobblers cross that looked set for an unmarked Boateng.
Trying again to add a fourth, Michael Smith fizzled a low shot wide of the mark after picking up a route-one ball from the defence.
Despite the scoreline Chesterfield were equal to everything Northampton tried, Grimshaw even matched Smith’s effort, blasting his own edge-of-the-area effort off-target.
Allinson was forced into acrobatics by David Buchanan, the ‘keeper got his finger tips to a long-range strike from the full-back that looked destined for the top corner.
Having been found on the flank by Nolan, Donohue took a touch and drove a low cross through the box but Smith dived to the pitch and grasped it safely.
In one last attempt to salvage something from the match Chesterfield piled forward, a Donohue cross met Ched Evans but his volleyed attempt smashed against Lewin Nyatanga and sailed out for a corner.
Northampton: A. Smith, Buchanan, Diamond, K.Anderson (Wylde), Boateng (P. Anderson), Richards (C), O'Toole, Nyatanga, M.Smith, Taylor, Eardley
Subs not used: Cornell (gk), McCourt, Beautyman, Phillips, McDonald
Chesterfield: Allinson, El Fitouri, Evatt (C), Anderson, Donohue, Jones (Mitchell), Gardner (Angel), Grimshaw, Nolan, Fuapala, Dennis (Evans).
Subs not used: Duke (gk), Hird, Simons, Brown