Chesterfield were cruelly punished for a host of missed opportunities when Gavin Tomlin gave Southend United victory seven minutes from time at the Proact Stadium.
The Spireites battled hard and created a raft of good opportunities but were unable to find a way past Paul Smith in the visitor’s goal.
Marc Richards came closest for Paul Cook’s side when he rattled the crossbar from 30 yards.
The result sees Paul Sturrock’s Shrimpers do the double over Chesterfield who slip further behind in the race for the play-off spots in League Two.
New recruits Armend Gnanduillet, Richard Brindley and the returning Conor Townsend all had to settle for a place on the bench as Cook named an unchanged side to that which swept aside Northampton Town two weeks ago.
The Spireites benefited from a weekend off when their trip to Torquay was postponed due to a waterlogged pitch.
And they were almost caught out early on when a long throw from Ryan Leonard caused confusion in the Chesterfield back line. The ball wasn’t cleared and goalkeeper Tommy Lee had to be alert to stop a point blank effort from Tomlin after Barry Corr’s knock down.
The home side found their rhythm midway through the first half after a sluggish start.
Adhering to their manager’s request to press Southend higher up the field, Whitaker robbed the ball off an unsuspecting Leanord and found Richards on the edge of the box, whose powerfully driven shot sailed over Paul Smith’s goal.
Craig Clay cut inside and unleashed a left-footed effort that was never going to trouble the Southend goalkeeper before Jay O’Shea saw his shot blocked by Chris Barker.
The Shrimpers continued to look dangerous on the break and Kevan Hurst had a shot that went well wide of Lee’s goal.
It was the hosts, however, who came closest to breaking the deadlock when Richards’ thunderous 30-yard free-kick smacked the crossbar with Smith appearing to get the tips of his fingers to the ball.
The striker had another opportunity moments later but Smith fisted away his 25-yard strike as the half drew to a close.
Southend came out of the traps the more lively of the two sides but it was Chesterfield again who looked more threatening.
Danny Whitaker’s carefully angled effort from the edge of the area narrowly goes wide of Smith’s left hand post, with the keeper looking on.
Richards sniffed out an opportunity after Tendayi Darikwa’s nod down wasn’t cleared, but he was charged down quickly by Smith who dived bravely at the striker’s feet.
And the visiting keeper had to be on his toes to prevent a dangerous cross from Nathan Smith from finding its way through to Richards.
Smith went another marauding run before cutting inside and testing Smith down low at his near post.
Substitute Jack Lester, who replaced Darikwa shortly after the hour, and Richards combined to set-up Whitaker with a shooting opportunity from 18 yards but the midfielder’s curling strike didn’t miss by much.
The front two of Lester and Richards were causing Southend’s defenders all sorts of problems and nearly fashioned an opening before the latter was harshly adjudged to have committed a foul.
O’Shea blazed one over the bar after a neat interchange involving Richards, while Michael Spillane tested Lee with a dipping shot from distance.
And, completely against the run of play, Tomlin raced clear after Michael Timlin dispossessed Sam Togwell to slot under Lee to give Southend the lead.
Gnanduillet came off the bench and missed a golden opportunity late on with a header before he had a shot blocked in goalmouth scramble.
Smith produced a great save late on to prevent Townsend from gaining a deserved point for the Spireites.
Spireites (4-2-3-1): Lee; Hird, Smith, Cooper, Trotman (Gnanduillet 86); Togwell, Clay; Darikwa (Lester 63), Whitaker (Townsend 80), O’Shea; Richards
Subs not used: Barrington, Randall, Brindley, Wafula
Shrimpers (4-4-2): Smith; Clohessy, Spillane, Cresswell, Hurst, Phillips, Leanord, Barker (c), Timlin, Corr, Tomlin
Subs not used: Straker, Harris, Prosser, Bentley, Spicer, Woodyard, Njie
Referee: Mark Heywood
Attendance: 4,817 (291)