A second-half goal saw Chesterfield fall to a 1-0 home defeat against arch-rivals Mansfield Town.
Mal Benning scored the only goal of the game when his left-footed effort deflected past Aaron Ramsdale and into the far corner of the net.
Chesterfield threw men forward in the closing stages, but were unable to fashion an equaliser.
Jack Lester made three changes to the team which started the 2-2 draw at Morecambe on Tuesday night and included Ian Evatt in his starting XI for the first time since December.
In front of a packed Proact Stadium, Mansfield’s Danny Rose missed the first big opportunity to open the scoring when he was found unmarked in the box by Benning but struck his effort straight at Ramsdale.
Chesterfield’s big chance came when Krystian Dennis’ flick-on found Laurence Maguire, who had stayed up from a free-kick, but the Spireites centre-half poked his effort straight at Conrad Logan, while Zavon Hines failed to capitalise on the rebound.
Just before the interval, Chesterfield went close again when Dennis did brilliantly to collect a long ball and force Logan into another smart save.
The second half started quietly, with the Spireites forced to do a significant amount of defending. That forced the Spireites boss to bring Chris O’Grady on for Hines and change to a more attacking shape.
The switch almost worked straight away when Dennis nearly found his new strike partner with a dangerous cross inside the box which forced some crucial defending from Pearce.
But it was Benning who finally broke the deadlock after 67 minutes when he burst forward into the area and his low shot took a deflection on its way past Ramsdale into the bottom corner.
Lester immediately reacted by turning to Louis Dodds and then Jak McCourt off the bench in the hope of getting back into the game.
And the Spireites went close to grabbing an equaliser when Dodds pounced on a loose ball outside the box. Although his initial shot looked wayward, Dennis went agonisingly close to deflecting it inside the far post.
Heading into the final ten minutes, Logan was forced into another save from a Maguire header while a McCourt volley also flew over the bar.
Midfielder Louis Reed was shown a red card in stoppage time for a cynical challenge but was instantly given a reprieve when referee Darren Drysdale realised a flag has been raised for off-side.
Despite more late pressure on the Mansfield goal, the visitors held on to claim victory.
Chesterfield: Ramsdale, Talbot, Evatt, Maguire, Brown (Dodds 69) Weir (McCourt 72), Reed, Smith, Dennis, Hines (O’Grady 58), Kellett
Unused subs: Anyon, Dodds, Rowley, Barry, McCourt, Nelson
Mansfield: Logan, Benning, Diamond, MacDonald, Rose, Potter, White (Bennett 32), Pearce, Hemmings (King 85), Atkinson, Mellis (Hamilton 53)
Unused subs: Olejnik, Hunt, Angol, Byrom
Ref: Darren Drysdale
Attendance: 7,967 (2,617 away fans)