The Spireites have moved into the play-offs with a 1-0 win against Grimsby Town at Blundell Park.
Dilan Markanday’s low cross was put into the back of the net by Harvey Rodgers to secured an eighth game unbeaten in all competitions.
Paul Cook made two changes to last Saturday’s side as Devan Tanton and Ronan Darcy came in for Vontae Daley-Campbell and Liam Mandeville.
Charles Vernam tried his luck early on with a curling effort from the edge of the area; it failed to troubled Zach Hemming and cleared the crossbar.
Chesterfield’s first opportunity came when Lewis Gordon’s cross found Naylor at the back post – his header landed on the roof of the net.
Hemming was called into action for the first time in the 20th minute, tipping Jaze Kabia’s shot over and out for a corner.
Darcy was presented with a golden chance to open the scoring just before the hour mark when a stray ball rolled to him at the edge of the area.
He looked to place the ball into the bottom corner, but side-footed his effort just wide of the post.
Grimsby created one more chance before the break when Kieran Green’s pinpoint cross was glanced past the far-post by Kabia.
Early into the second period, Hemming was forced into a couple of saves as he denied Jamie Walker and Vernam.
In the 53rd minutes, a long ball over the top of the Grimsby defence was chased down by Bonis before the striker was brought down on the edge of the area by Christy Pym. Referee Martin Woods gave a free-kick in the Spireites’ favour and gave the home goalkeeper a straight red card.
The subsequent set-piece from John Fleck was sent substitute Charlie Casper’s crossbar.
Casper’s first bit of action came in the 69th minute as he reacted well to palm away a Darcy half-volley.
Two minutes later, Chesterfield took the lead. Markanday dazzled along the right-hand side, got away from his defender, and fired in a low cross.
The last touch came off Rodgers and found a way into the back of the net.
The Spireites dominated proceedings towards the end of the game and even hunted down a second goal.
Markanday won back possession late on, drove towards the penalty area and skewed a shot wide of the mark.
Despite eight minutes of additional time, the Blues stayed strong to come away with the three points.
Chesterfield: Hemming, Tanton, Dunkley ©️ (Donacien 73), McFadzean, Gordon, Naylor, Fleck, Markanday, Darcy (Mandeville 85), Berry (Duffy 85), Bonis.
Unused Substitutes: Boot, Daley-Campbell, Hobson, Dickson.
Attendance: 7,407 (1,184 away)
