It was all going so well until, all of a sudden, it wasn’t.
And then it all went very, very wrong.
Sheffield United found themselves a goal down at the break before putting four past Town keeper Ryan Fulton.
The onslaught wasn’t altogether unexpected.
Sheffield Wednesday boss and chairman unhappy after attackers leave for Premier League
Latest on Pierce Charles contract talks as Darren Moore confirms Sheffield Wednesday transfer possibility
Sheffield United left baffled about key man's injury ahead of big Middlesbrough trip
Former Sheffield Wednesday defender Lewis Gibson signs for League One club on loan from Everton
Sheffield Wednesday transfer admission after latest injury setback
Chesterfield hit the front after two minutes with a fine goal from Jon Nolan.
It was a thunderbolt from the blue that temporarily silenced the masses of Blades behind Simon Moore’s goal, the goalkeeper utterly helpless to stop Nolan’s half volley.
The Spireites looked confident, the three in midfield were finding space and both Ched Evans and Gboly Ariyibi were up for it.
Evans in fact was perhaps a little too up for it, trying to do too much at times.
Cracks started to appear when the hosts began to give the ball away too easily and retreat to the edge of their box, inviting pressure.
In the first half they were let off the hook by a United side sending crosses here, there and everywhere but crucially not to dangerous areas.
For all their possession, United were lucky not to go in 2-0 down at the break, Ian Evatt’s towering back post header crashing onto the bar.
Presumably having received a rollicking, the Blades came out sharply whereas Town sat deep and attempted to counter, Evans forcing a save from Moore.
Fulton had to be at his best to keep out Billy Sharp on 54 minutes, but there was nothing he could do when Fleck crossed and Kieron Freeman arrived, lost by marker Dion Donohue, and nodded in.
Still the floodgates didn’t open, Chesterfield unfortunate not to retake the lead when Moore partially saved an Evans’ shot and Jake Wright headed off the Blades’ line.
It all started to unravel when Evans limped off with an ankle injury.
And the game turned entirely when Nolan too picked up a knock, Ritchie Humphreys made a surprise appearance and promtly gave the ball away, United going straight down the pitch through Fleck whose 25 yard drive somehow beat Fulton.
Less than a minute later Mark Duffy crossed and Sharp headed home – game over.
Leon Clarke’s classy 25-yard sidefoot finish was just the icing on the cake, United too strong and too ruthless for their beleaguered hosts.
Strength in depth, quality in the final third and belief were the big differences on another bleak day for Town.
Chesterfield: Fulton 5, Liddle 5, EVATT 6, Anderson 5, Donohue 4, Dimaio 4, O’Neill 4, Nolan 5 (Humphreys 69), Ariyibi 4, O’Shea 4, Evans 6 (Dennis 66).