Tom Naylor was the hero for the Spireites as he completed a stunning turnaround for the home side after Hartlepool had found themselves two goals to the good inside six minutes.
Emmanuel Dieseruvwe and Anthony Mancini scored within minutes of each other to put Askey’s side into a promising position only for Ryan Colclough to hit back 10 minutes later.
It was a game which swung from one way to the other in the opening 20 minutes but would ultimately swing in Chesterfield’s favour after an injury to Mancini.
The Frenchman was forced off with what looked like a hamstring injury as the home side dominated things from there on, grabbing an equaliser through Jamie Grimes early in the second half.
And despite, seemingly, doing enough to escape with a draw, Pools were hit with a stoppage time blow as Naylor squeezed in a winner for the Spireites.
Hartlepool boss Askey suggested in the wake of their victory over AFC Fylde that the Bank Holiday Monday trip to Chesterfield would provide him with a much better idea of where his team were at, despite heading to North Derbyshire on the back of four straight wins.
In reality, this felt like an early measuring stick for both sides with Chesterfield, for many, the early season favourites to claim that elusive, singular, automatic promotion spot this season while Pools had made the early season running with four straight wins.
A fifth straight league win would have been the first time in 12 years a Hartlepool side had managed such a feat, dating back to their time in League One.
To do so, however, Askey had to contend with two enforced changes to his side with both Dan Dodds and Chris Wreh unable to make the quick turnaround having picked up knocks less than 48-hours earlier against Fylde.
Dodds was replaced by summer signing Kieran Wallace who was making his first start since arriving from Mansfield Town with Joe Grey given the nod up front to partner Dieseruvwe.
Grey has done well coming off the bench in recent weeks with Askey showing his faith in the young forward by giving him the starting shirt ahead of the returning Josh Umerah, who was back on the bench following his three-match suspension.
The Spireites were spearheaded by summer signing Will Grigg, with the former Sunderland striker making a positive start to life in the National League but it was Hartlepool who made the positive start at the SMH Group Stadium as they flew out of the traps into a two-goal lead within just six minutes.
Momentum can be a funny thing in football, one way or the other, and Hartlepool certainly had it heading into the game which translated onto the pitch when Dieseruvwe opened the scoring.
Having given possession away cheaply, Pools won things back from a throw-in before Callum Cooke showed great tenacity to keep a dead ball alive on the left-hand side to prod a ball into the path of Dieservuwe just inside the Chesterfield half.
The striker still had it all to do as he wrestled his way by Ash Palmer to lead a foot-race with the defender and Dieseruvwe drove into the box before perfectly executing into the far corner to continue his blistering start to life in a Pools shirt.
The sold-out 1,030 in the away end barely had time to find their seats again before Pools doubled their lead with another excellent team goal.
Dieservuwe held things up well on halfway before releasing Mancini down the right. The Frenchman drew a defender in just enough before sliding a ball into Grey who advanced towards the edge of the area before the youngster played a clever ball in-between two Chesterfield defenders to find Mancini who had escaped into a pocket of space.
The midfielder took one touch in his stride to set himself before delicately rolling the ball into the bottom corner to send the travelling supporters into delirium.
And Askey’s side might have added a third in the tenth minute when Mancini and Grey hassled well to win a free kick which saw David Ferguson’s cross headed over at the near post by Tom Crawford.
The Spireites saw their first sight of goal soon after that missed opportunity as Jeff King’s hopeful ball forward gave Grigg a chance to test Emmanuel Onariase for pace, but the striker’s heavy touch allowed Joel Dixon to gather.
The home side soon found a way back into things though after a series of crosses into the box – with Pools unable to really clear their lines before Liam Mandeville curled in from the right to find Colclough who had found space behind Onariase to power a header home.
A frantic start settled but not for the reasons Hartlepool wanted as they were forced into a significant change with Mancini being taken off.
Pools had looked to spring a counter-attack with Grey charging down the right but in trying to support his team-mate, Mancini pulled up and clutched at his hamstring as Askey was made to shuffle his pack.
It was a change which disrupted the flow to Hartlepool’s rhythm as the Spireites took control of the game.
Colclough, who troubled Charlie Seaman all afternoon, skipped inside to find the side netting before King fired over from a swift counter-attack – Colclough again the architect.
The half finished almost as it started with chances at both ends as Paul Cook’s side ought to have levelled when Mandeville, who, perhaps, was fortunate to still be on the field after a heavy challenge on Tom Crawford, picked out Michael Jacobs on the penalty spot but his header was straight at Dixon.
Pools then went up the other end as Grey found space on the left and was able to cut in before seeing an effort blocked into the path of Crawford who fired off target.
The half-time whistle allowed chance for everybody inside the SMH Group Stadium to grab their breath following a pulsating 45 minutes.
But within minutes of the restart Chesterfield were level.
Dixon flapped at a lofted ball into the area before clattering into Colclough and, while escaping punishment for that, form the subsequent corner the home side converted as Grimes headed in from Naylor’s effort which came back off the bar.
It was the perfect start to the second half for Cook’s side who had their tails up and dominated proceedings from there on.
Mandeville, who was pulling the strings by this point, slipped a smart ball into Colclough on the left of the penalty area to bring a good save from Dixon at his near post.
Mandeville then searched for Naylor with another cross from the left before Naylor hit the ground under pressure from Ferguson with the Hartlepool captain made to wait anxiously before the referee waved things away.
Colclough continued to cause Pools problems when he capitalised on a loose clearance from Seaman but fired over.
It took Pools until the hour mark before then were able to find a way into the Chesterfield half when Ferguson won the ball on halfway to release Cooke who drove into the box before seeing an effort well blocked by Palmer before the Spireites re-established their second half dominance, Colclough driving into the side netting.
The home side did have the ball in the back of the net, and it was Colclough again who scrambled in from King’s cross only for the offside flag to come to Hartlepool’s rescue.
Cook shuffled his pack with the introduction of Armando Dobra who was straight into the action when skipping by Crawford to pick out Colclough in the box but he was wild with his finish when curling wide.
Mercifully for Pools that was Colclough’s final act in the game as he was substituted before Pools had half a chance through Dieservuwe who met Brody Paterson’s cross at the near post but diverted over the bar.
Edon Pruti did well to head away a fierce effort from James Berry before Berry put the game on a plate for Grigg in stoppage time when his excellent cross from the left found the striker unmarked in the six-yard box but he somehow managed to glance his header wide of the far post.
Hartlepool might have thought they had survived and would take a point home for their efforts but they were dealt a gut-wrenching blow soon after as Naylor completed the turnaround for Cook’s side.
Pools were unable to clear a long ball forward as the ball fell into the path of Naylor in the area and his strike at goal squeezed in at the near post despite Dixon’s efforts as Hartlepool suffered their first defeat since the opening day of the season.