Jay O'Shea scored against his former club as Chesterfield extended their winning run to four league games with victory at promotion-chasing Port Vale.
On-loan O'Shea, who had a spell at Vale Park in 2011, fired the Spireites ahead on his debut just before the break.
Soon after Ashley Vincent scuffed a shot for Vale, Tendayi Darwikwa made it 2-0 by heading in Marc Richards' cross.
The hosts piled on the pressure but Tom Pope's header into the hands of Tommy Lee was the closest they came.
Defeat ends Vale's unbeaten run of five matches in the league, but they still retain their second place in League Two.
VIEW FROM THE DRESSING ROOM
Chesterfield manager Paul Cook told BBC Radio Sheffield:
"We're delighted to get three points. Three points is vital in the league.
"I thought it was a thoroughly professional team performance from all of the players involved, including the subs and the lads that never got on.
"We've come today and we deserved to win the game."
Live Text Commentary
Full Time The final whistle is blown by the referee.90:00 +4:07
Danny Whitaker takes a inswinging corner.89:44 Booking
Booking The referee shows Jennison Myrie-Williams a yellow card for unsporting behaviour.89:36
Foul by Jennison Myrie-Williams on Drew Talbot, free kick awarded. Sam Hird restarts play with the free kick.82:03 Substitution
Substitution Danny Whitaker replaces James O'Shea.82:03
Foul by Clayton McDonald on Marc Richards, free kick awarded. Free kick taken by Sam Hird.77:49
Foul by Sam Hird on Tom Pope, free kick awarded. Chris Shuker crosses the ball in from the free kick, Sam Hird makes a clearance.75:45 Substitution
Substitution (Port Vale) makes a substitution, with Louis Dodds coming on for Doug Loft.75:25 Substitution
Substitution Craig Clay joins the action as a substitute, replacing Mark Randall.74:23
The assistant referee flags for offside against Marc Richards. Chris Neal takes the indirect free kick.73:07
Richard Duffy takes a inswinging corner to the near post, clearance by Sam Hird.71:05 Substitution
Substitution Brennan Dickenson joins the action as a substitute, replacing Luis Boa Morte.70:28
Tom Pope is ruled offside. Tommy Lee restarts play with the free kick.68:53
The ball is crossed by Ryan Burge, Tom Pope takes a shot. Inswinging corner taken from the right by-line by Ryan Burge, save by Tommy Lee. Tommy Lee makes a save.68:53 Booking
Booking The referee books Luis Boa Morte for unsporting behaviour.68:39
Foul by Luis Boa Morte on Chris Shuker, free kick awarded.66:59
Foul by Richard Duffy on Luis Boa Morte, free kick awarded. Mark Randall fires a strike on goal direct from the free kick,65:04
Ashley Vincent is flagged offside by the assistant referee. Indirect free kick taken by Tommy Lee.63:09
The assist for the goal came from Marc Richards.63:09 Goal scored
Goal! - Tendayi Darikwa - Port Vale 0 - 2 Chesterfld Tendayi Darikwa grabs a headed goal from inside the six-yard box. Port Vale 0-2 Chesterfield.
Chris Shuker is penalised for handball and concedes a free kick. Marc Richards shoots direct from the free kick, save made by Chris Neal.59:49
Corner taken right-footed by Mark Randall to the near post, clearance made by Robert Taylor.58:58
Ashley Vincent is ruled offside. Indirect free kick taken by Tommy Lee.58:19 Substitution
Substitution (Port Vale) makes a substitution, with Chris Shuker coming on for Kingsley James.57:53 Substitution
Substitution Robert Taylor comes on in place of Calvin Andrew.55:41
Corner taken left-footed by Ryan Burge, Clayton McDonald produces a header from inside the area that goes over the bar.52:47
Calvin Andrew takes a shot. Tommy Lee makes a save.50:56
Inswinging corner taken by Luis Boa Morte from the right by-line, Chris Neal makes a save.48:14
Drew Talbot concedes a free kick for a foul on Ashley Vincent. John McCombe concedes a free kick for a foul on Drew Talbot. Free kick crossed right-footed by Luis Boa Morte from right wing.45:01
The game restarts for the second half.45:00 +1:09 Half time
Half Time The whistle is blown to end the first half.45:00 +0:08
Corner taken right-footed by Mark Randall from the right by-line to the near post, clearance by Kingsley James.38:53
Outswinging corner taken by Ryan Burge.36:22
Assist on the goal came from Marc Richards.36:22 Goal scored
Goal! - James O'Shea - Port Vale 0 - 1 Chesterfld James O'Shea fires in a goal from inside the area to the bottom right corner of the goal. Port Vale 0-1 Chesterfield.35:25
Foul by Calvin Andrew on Luis Boa Morte, free kick awarded. The free kick is delivered left-footed by Luis Boa Morte from left wing, clearance by John McCombe.33:33
Free kick awarded for an unfair challenge on Calvin Andrew by Sam Hird. Direct free kick taken by Clayton McDonald.32:25
Luis Boa Morte takes the inswinging corner, Ryan Burge makes a clearance.27:49
Unfair challenge on James O'Shea by Clayton McDonald results in a free kick. Marc Richards shoots direct from the free kick, save by Chris Neal.26:57
The referee gives a free kick against Kingsley James for handball. Sam Togwell restarts play with the free kick.25:51
Sam Hird takes a shot. Save made by Chris Neal.21:14
Ashley Vincent takes the inswinging corner, clearance by Marc Richards.16:50
Mark Randall takes a inswinging corner from the left by-line to the near post, Calvin Andrew manages to make a clearance. Corner taken by Mark Randall from the left by-line played to the near post.11:20
Mark Randall takes a shot. Chris Neal makes a save.9:57
Inswinging corner taken by Ryan Burge from the right by-line played to the near post, Tendayi Darikwa manages to make a clearance. Outswinging corner taken left-footed by Ryan Burge from the left by-line to the near post, clearance by Marc Richards.9:13
Sam Hird challenges Ashley Vincent unfairly and gives away a free kick. Ashley Vincent crosses the ball from the free kick right-footed from left channel.7:59
Marc Richards is ruled offside. Indirect free kick taken by Chris Neal.5:41
The assistant referee signals for offside against Calvin Andrew. Indirect free kick taken by Tommy Lee.4:50
Ryan Burge takes the outswinging corner, save by Tommy Lee.4:30
Tom Pope takes a shot. Save by Tommy Lee.3:58
Luis Boa Morte takes the inswinging corner, save made by Chris Neal.3:25
Mark Randall takes a shot. Save by Chris Neal.1:32
Foul by Doug Loft on Drew Talbot, free kick awarded. Free kick taken by Mark Randall.0:00
The ref blows the whistle to start the match.
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