Second-half goals from Jordan Slew and Matt Warburton did the damage at The Shay.
This defeat all but ends the Spireites’ hopes of finishing in the top three which means they are going to have to do it the hard way if they are to win promotion. The gap to Wrexham and Halifax is now eight points and seven points respectively which, with just five games remaining, is probably too big to overturn.
Town are also back to looking over their shoulder a little bit again as well. Grimsby and Notts County are right on their tails and in-form Dagenham and Redbridge, who are eighth, are only five points behind.
And with some tough games coming up, it makes Saturday’s match at home to bottom club Dover Athletic ‘must-win.’
It is hard to believe that this is what it has come to after topping the table for a good chunk of this season.
This game was won and lost in both boxes. Chesterfield didn’t take their chances and Halifax did.
The Shaymen’s goals came totally against the run of play after the visitors had squandered some good chances. In fairness, they came up against an impressive goalkeeping display from home stopper Sam Johnson, who now has 18 clean sheets this season.
The first-half was fairly even, Billy Waters and Harvey Gilmour fired wide for the hosts and Gavin Gunning made an outstanding block from a scramble. But Chesterfield threw some punches of their own with Tom Denton having a goal ruled out and Liam Mandeville forced an excellent reaction save from Johnson.
After the break, Town played some of their best football so far under Cook and there only looked like being one winner. Joe Quigley blazed over and Akwasi Asante was denied by the legs of Johnson as the home fans became frustrated.
But then came two soft goals in three minutes and the game was done.
Chesterfield have actually played a lot worse than this and won this season but it was a script which is getting all too familiar.
Chesterfield thought they had taken the lead in the first-half when Denton headed in Mandeville’s deep cross at the back post but the striker was penalised for an apparent foul. On first viewing the decision certainly looked harsh and Cook felt the same at full-time.
There was another controversial moment in the second-half when Asante appeared to be hauled down on the edge of the box when he was in on goal but nothing was given.
Both decisions were big moments in the game and they both went against the visitors.
Gunning, who has been a rock in the first-half, was forced off at half-time with a calf problem. Do Chesterfield concede that first goal with him on the pitch? I don’t think so.
Jim Kellermann, who was on a yellow, was substituted not long before Halifax’s opener and he had given a decent account of himself so that was two changes to the spine of the team.
Laurence Maguire (ankle) and Saidou Khan (neck) did not make the squad.
Loach; Williams, Gunning (Miller, 46), Grimes; King, Weston, Kellermann (McCourt, 70), Whittle; Mandeville; Asante, Denton (Quigley, 60). Unused subs: Oyeleke, Whelan.