Rotherham moved to within one point of the automatic promotion places with a deserved victory over Chesterfield.
The Millers dominated the first half and striker Daniel Nardiello was denied by both the post and an excellent save from visiting keeper Tommy Lee.
Captain Johnny Mullins put the hosts ahead after the interval with a header from David Noble's corner.
Armand Gnanduillet should have equalised with the final action of the match but he miscued his header.
Steve Evans's side were in control throughout and are now just one point behind third-placed Burton Albion.
Chesterfield have slipped to 12th and are eight points outside the play-offs.
VIEWS FROM THE DRESSING ROOM
Rotherham United boss Steve Evans told BBC Radio Sheffield:
"Apart from the (lack of) goals I don't think the performance gets much better.
"We made a number of chances, arguably we could have had a penalty, but we got the victory and that's for the supporters.
"That's my first Rotherham-Chesterfield derby and what an atmosphere.
"It was such a dominant performance and that takes nothing away from (Chesterfield boss Paul) Cook, he's got some wonderful football players that play for Chesterfield."
Chesterfield manager Paul Cook tells BBC Radio Sheffield:
"The best side won comfortably, we have no issues with that. Congratulations to Rotherham.
"I learnt a lot about my players today and it wasn't very good.
"We waited 60 minutes for Rotherham to score and then we started to have a go. It's not good enough.
"If you don't have desire to play football you get beat. Some of our players late on showed they do have it. One or two certainly showed they didn't and that's sad."
Live Text Commentary
Full Time The final whistle is blown by the referee.90:00 +4:19
The ball is sent over by Drew Talbot, Liam Ridehalgh gets a block in. Corner taken by Conor Townsend, Armand Gnanduillet has an effort at goal from close in which goes wide left of the target.90:00 +3:26 Substitution
Substitution (Rotherham) makes a substitution, with Courtney Cameron coming on for Daniel Kearns.90:00 +2:29
Foul by David Noble on Drew Talbot, free kick awarded. Free kick crossed by Conor Townsend.90:00 +0:53
Unfair challenge on David Noble by Armand Gnanduillet results in a free kick. Direct free kick taken by Andy Warrington.89:14
The offside flag is raised against Jordan Slew. Free kick taken by Tommy Lee.86:49
Jordan Slew fouled by Liam Cooper, the ref awards a free kick. Strike comes in from Kari Arnason from the free kick.86:16
The ball is delivered by Conor Townsend. Centre by Richard Brindley, David Noble manages to make a clearance.85:57
Richard Brindley crosses the ball, clearance by Claude Davis.84:41
Andy Warrington restarts play with the free kick.84:41 Substitution
Substitution Jordan Slew comes on in place of Daniel Nardiello.84:41
The referee blows for offside.82:51 Substitution
Substitution Kayode Odejayi on for Alex Revell.81:41
The ball is swung over by Mark Bradley, save by Tommy Lee.81:17
The ball is crossed by Drew Talbot, clearance by David Noble.80:04
Effort on goal by Lee Frecklington from 18 yards. Save by Tommy Lee.79:08
Richard Brindley produces a cross.78:45
Marc Richards takes the direct free kick.78:45 Booking
Booking Lee Frecklington goes into the book for unsporting behaviour.78:23
Foul by Lee Frecklington on Armand Gnanduillet, free kick awarded.
The offside flag is raised against Daniel Nardiello. Tommy Lee takes the free kick.75:36
The ball is swung over by Daniel Nardiello, blocked by Nathan Smith. Outswinging corner taken from the right by-line by David Noble, Unfair challenge on Tommy Lee by Johnny Mullins results in a free kick. Tommy Lee restarts play with the free kick.73:59
Daniel Nardiello crosses the ball, Neal Trotman makes a clearance. Corner taken short by Daniel Kearns.73:01
Daniel Nardiello delivers the ball, clearance by Neal Trotman.72:27
Alex Revell fouled by Neal Trotman, the ref awards a free kick. David Noble takes the free kick.71:21
Outswinging corner taken by David Noble from the right by-line, clearance by Liam Cooper.71:06
Daniel Nardiello sends in a cross, Nathan Smith gets a block in.70:50
Unfair challenge on Alex Revell by Liam Cooper results in a free kick. David Noble restarts play with the free kick.69:57 Substitution
Substitution Richard Brindley comes on in place of Danny Whitaker.69:57
Sam Hird produces a cross, Close range header by Armand Gnanduillet goes wide of the left-hand post.69:16
Unfair challenge on Sam Togwell by Johnny Mullins results in a free kick. Free kick crossed by Conor Townsend.66:35
Sam Hird challenges Kari Arnason unfairly and gives away a free kick. Free kick taken by David Noble.64:43
Foul by Mark Bradley on Conor Townsend, free kick awarded. Conor Townsend crosses the ball from the free kick left-footed from left channel, Liam Ridehalgh makes a clearance.62:30
The ball is sent over by Liam Ridehalgh.61:39
Nathan Smith produces a cross, Effort on goal by Marc Richards from just inside the penalty area goes over the target.61:25
The ball is swung over by Marc Richards, Mark Bradley makes a clearance.59:12 Substitution
Substitution James O'Shea goes off and Armand Gnanduillet comes on.59:12 Substitution
Substitution Conor Townsend replaces Jack Lester.59:12
Effort from the edge of the box by Sam Togwell goes wide of the left-hand upright.56:45
The assist for the goal came from David Noble.56:45 Goal scored
Goal! - Johnny Mullins - Rotherham 1 - 0 Chesterfld A goal is scored by Johnny Mullins from close range high into the middle of the goal. Rotherham 1-0 Chesterfield.56:32
Corner from the right by-line taken by David Noble,54:14
Liam Ridehalgh sends in a cross, Header from deep inside the penalty area by Daniel Nardiello goes harmlessly over the crossbar.52:52
Centre by Mark Bradley, Neal Trotman manages to make a clearance.51:44
The ball is swung over by James O'Shea.51:12
Daniel Nardiello sends in a cross, save by Tommy Lee.49:37
Mark Bradley delivers the ball.49:11
David Noble fouled by Jack Lester, the ref awards a free kick. Liam Ridehalgh takes the direct free kick.47:57
The assistant referee signals for offside against Daniel Nardiello. Indirect free kick taken by Tommy Lee.47:33
The ball is crossed by Mark Bradley, clearance by Neal Trotman.45:57
Shot by Alex Revell from deep inside the penalty area misses to the right of the target.45:01
The referee gets the second half underway.45:00 +3:18 Half time
Half Time The referee calls an end to the first half.45:00 +1:30
The ball is swung over by Drew Talbot, Jack Lester takes a shot. Johnny Mullins gets a block in. Danny Whitaker decides to take a short corner.45:00 +0:14
The ball is delivered by Daniel Kearns.44:09
Daniel Kearns crosses the ball, clearance by Liam Cooper. Shot by David Noble from outside the box goes high over the target.41:41
Inswinging corner taken by David Noble, clearance by Liam Cooper.41:12
The ball is swung over by David Noble, Alex Revell takes a shot. Blocked by Drew Talbot. Corner taken by David Noble from the left by-line, clearance made by Drew Talbot. Inswinging corner taken by David Noble, Foul by Lee Frecklington on Nathan Smith, free kick awarded. Tommy Lee takes the direct free kick.39:43
Centre by Daniel Kearns, clearance by Liam Cooper. Inswinging corner taken right-footed by David Noble, Neal Trotman makes a clearance. Corner taken right-footed by David Noble.35:47
David Noble fouled by Sam Hird, the ref awards a free kick. Free kick taken by Liam Ridehalgh.33:46
David Noble takes the direct free kick. David Noble takes a shot. Blocked by Sam Togwell.33:46 Booking
Booking The referee shows Liam Cooper a yellow card.33:10
Free kick awarded for a foul by Liam Cooper on Alex Revell.32:35
Jack Lester is flagged offside by the assistant referee. Free kick taken by Andy Warrington.31:10
Drilled left-footed shot by Daniel Nardiello. Save made by Tommy Lee. Corner taken right-footed by David Noble, save by Tommy Lee. Claude Davis challenges Sam Togwell unfairly and gives away a free kick. Free kick taken by Tommy Lee.30:31
Danny Whitaker delivers the ball.29:33
The ball is delivered by Alex Revell, Neal Trotman gets a block in. Corner taken right-footed by David Noble, Claude Davis takes a shot. Save by Tommy Lee.27:01
Lee Frecklington is flagged offside by the assistant referee. Free kick taken by Tommy Lee.26:24
Effort from the edge of the area by Marc Richards goes wide of the right-hand post.25:48
Mark Bradley concedes a free kick for a foul on Nathan Smith. Liam Cooper takes the free kick.25:01
Marc Richards delivers the ball, Liam Ridehalgh makes a clearance.24:37
Kari Arnason delivers the ball, Liam Cooper manages to make a clearance.23:27
Marc Richards concedes a free kick for a foul on Kari Arnason. Liam Ridehalgh takes the free kick.22:49
James O'Shea produces a cross.22:07
Free kick awarded for an unfair challenge on Nathan Smith by Mark Bradley. Tommy Lee takes the direct free kick.21:00
Centre by David Noble, Sam Togwell gets a block in.20:14
The ball is crossed by Lee Frecklington, save by Tommy Lee.19:08
A cross is delivered by Daniel Nardiello. David Noble takes a shot. Liam Cooper gets a block in. David Noble takes the outswinging corner, Liam Cooper makes a clearance.17:22
David Noble produces a strike on goal direct from the free kick, save by Tommy Lee.17:22 Booking
Booking Sam Hird is booked.16:59
Free kick awarded for an unfair challenge on Daniel Nardiello by Sam Hird.13:53
The ball is swung over by Kari Arnason, save made by Tommy Lee.12:48
Drew Talbot delivers the ball, blocked by Claude Davis.12:06
The ball is swung over by Drew Talbot, clearance made by Mark Bradley.10:38
Daniel Kearns takes a shot. Blocked by Neal Trotman. Corner taken right-footed by David Noble from the left by-line, save by Tommy Lee.8:59
Mark Bradley sends in a cross, clearance by Liam Cooper.8:18
Alex Revell challenges Neal Trotman unfairly and gives away a free kick. Tommy Lee takes the free kick.7:40
The assistant referee flags for offside against Jack Lester. Andy Warrington restarts play with the free kick.7:04
The ball is delivered by Daniel Kearns, clearance by Liam Cooper. David Noble produces a left-footed shot from just outside the penalty box that goes wide left of the target.5:41
A cross is delivered by Liam Ridehalgh.4:32
Alex Revell delivers the ball.3:28
Daniel Nardiello has an effort at goal from just inside the penalty area that bounces off the post.2:53
Jack Lester takes a shot. Save made by Andy Warrington.2:04
Drew Talbot handles the ball and concedes a free kick. Free kick taken by David Noble.0:00
The game kicks-off.
Live data and text provided by our data suppliers