A first-half goal from Ethan Chislett condemned the Spireites to a 1-0 defeat at Vale Park against Port Vale.
The midfielder ran through on goal before slotting home in the 11th minute to give the home side a slender victory.
Paul Cook made two changes from the previous fixture with Chey Dunkley returning as he replaced Jamie Grimes and Jenson Metcalfe making his first start in place of the suspended Darren Oldaker.
Chesterfield created a couple of early half-chances. Firstly, Metcalfe’s lovely ball up the pitch was flicked on by Will Grigg and then saw Armando Dobra’s shot blocked by the home defence.
Five minutes later, another searching Metcalfe pass found Devan Tanton on the right-hand side. His cross just evaded Grigg and was headed wildly over by Dobra.
Port Vale soon assumed control of proceedings and scored in the 11th minute. Lorent Tolaj sent Chislett through on goal and the midfielder slotted his effort beyond Ryan Boot.
The South African native immediately went on the prowl for a second and saw a curling effort palmed away by Boot and a header that cleared the crossbar.
Around the half-hour mark, the Blues started to find their footing back into the game with some sustained possession.
In first half added time, Lewis Gordon’s cross was diverted wide by Grigg, who went down in pain. He was soon replaced by Kane Drummond.
The second half was very scrappy with the Spireites trying to get back on level terms, but the hosts almost made it two when Benicio Baker-Boaitey’s strike was well held by Boot.
Dilan Markanday dug out a cross that found James Berry at the back-post, but the winger’s shot was deflected over the crossbar.
Boot was called into action twice either side of the hour mark to deny Tolaj twice.
With all the pressure coming from the away side, Mike Jones sent a volley over the crossbar from the edge of the box as the clock ticked over into added time.
After the 100th minute came up, referee Neil Hair blew the whistle to condemn Chesterfield to defeat.
Chesterfield: Boot, Tanton, Naylor ©️, Dunkley, Gordon, Banks (Metcalfe 83), Metcalfe (Araujo 83), Markanday (Jacobs 83), Dobra, Berry (Mandeville 64), Grigg (Drummond 45+3).
Unused Substitutes: Thompson, Williams.
Attendance: 7,976 (1,434)
