The Spireites fell to a fourth straight league defeat at home to Scunthorpe United, the away side's pace and power leading them to a 3-0 Proact result.
All-square at the break, the Iron broke the deadlock shortly afterwards through Josh Morris when a swung-in freekick managed to sneak into the far corner of the net, the lead doubled on the hour when Kevin van Veen ran through and finished.
Substitute Sam Mantom scored with calmness in the final ten minutes to confirm the Spireites' loss as their slump continued.
Ricky German made his first professional start for the club and the Spireites matched their opponents in a keenly-contested opening half but goals from Josh Morris, Kevin van Veen and Sam Mantom won it for the visitors.
Scunthorpe had the first chance of the game after six minutes when Morris picked out Paddy Madden with a cut back but his shot was deflected just wide of the post.
The league’s top scorer Morris had a decent effort from a free kick 30 yards out but it curled just over the bar.
Van Veen broke through the middle and found an opening on the edge of the box but his driven shot fizzed wide on 12 minutes as Scunthorpe took control of the early exchanges.
Chesterfield came back into it and Ched Evans had the Spireites' first chance on the 18th minute when he turned and shot from 25 yards out but his powerful effort was straight at the 'keeper.
Evans then had the best chance up until that point. Gboly Ariyibi’s delicious first time cross from the right was perfectly placed for the striker but his glancing header was just wide of the mark.
The Spireites began to string some attacks together and German almost opened his account as the ball came across to him at the edge of the box. He tried to bend the ball into the bottom corner but it was the wrong side of the post.
The majority of the Proact thought the Spireites had taken the lead just before half time when Ariyibi carved himself some space inside as crowded box to get a shot away which was deflected onto the side netting and rolled behind the goal.
Scunthorpe were looking dangerous on the break. They quickly burst down the other end and Madden found himself one on one with Fulton who did well to save and divert the ball away from danger.
The league leaders began the second half brightly and took the lead on 49 minutes when Morris’ freekick from beat went over every one and ended up dropping into the bottom corner. Scunthorpe took charge and were putting Chesterfield under a lot of pressure.
They deservedly doubled their lead on the hour when Duane Holmes broke forward and slotted the ball through to Van Veen and the Dutchman buried the ball into the bottom corner.
Van Veen almost doubled his tally six minutes later but his attempt trickled wide as the Iron remained in complete control.
The Spireites pushed to get back into the game. Gardner looked bright after replacing German making positive runs and linking up well with Donohue on the left. He burst through the middle and created space for the shot but it was blocked as Graham Alexander’s team restricted the Spireites to very little.
Scunthorpe settled it once and for all when Van Veen played a lovely Crossfield ball to substitute Mantom who was through one on one and placed the ball past Fulton.
The Spireites pressed for a consolation and didn’t give up but couldn’t break down a very good Scunthorpe defence and ultimately showed why they are the league leaders.
Chesterfield: Fulton (gk) - Donohue, Hird, Anderson, O'Neil (Simons 82') - O'Shea (Mitchell 70'), Liddle (c), Nolan, Ariyibi - German (Gardner 61'), Evans
Subs not used: Allinson (gk), Evatt, Dimaio, Graham
Scunthorpe United: Daniels (gk) - Wallace, Mirfin, Dawson (c) (Smallwood 80'), Madden, Van Veen, Morris, Bishop, Holmes (Mantom 73'), Townsend, Sutton
Subs not used: Anyon, Hopper, Goode, Margetts, Ness
Scunthorpe United: Morris 49', Van Veen 60', Mantom 85'
Attendance: 6,328 (1,152 away fans)