The Spireites would live to rue a host of missed chances at Rodney Parade in a result which tightened matters at the top of League Two.
No less than five teams remain on the same number of points and just three points separate table-toppers Oxford United and eighth-placed Newport.
Paul Cook’s side weren’t at their best but put in a workmanlike performance and looked the more likely side to claim a win after Jimmy Ryan had cancelled out Danny Crow’s opener with his first league goal of the season.
But, when Liam Cooper was adjudged to have hauled down Conor Washington inside the penalty area, their task was made infinitely harder. And, after awarding the penalty, referee Mark Haywood had no other option but to send the centre-half off.
Adam Chapman confidently sent Tommy Lee the wrong way with the resulting spot kick before Andy Sandell made the game safe late on. Marc Richards made it a lively last few minutes when he pulled a goal back in the first minute of injury time but Chesterfield couldn’t find an equaliser.
Cook made just one change to the starting line up that drew 0-0 at home to Northampton midweek.
Callum McFadzean, the left sided player on loan from Sheffield United, replaced Ritchie Humphreys in a like-for-like swap in the back four on a day when the Spireites manager only named six substitutes.
The Newport faithful were in good voice prior to the kick-off and their side duly responded with Washington finding room in the channels. It would prove a good battle between he and Drew Talbot as the afternoon went on.
The hosts, who had barely broken sweat, found themselves in front when Crow was first to meet Robbie Willmott’s inviting free kick from the right and directed his header in to the bottom left corner past the dive of Tommy Lee.
After an unsteady start, the Spireites began to find their feet. But the hosts could have doubled their advantage when Christian Jolley pounced on Willmott’s fizzing cross from the left. Jolley got in front of McFadzean but scuffed his shot and the chance went begging.
Cook’s side tried their best to play their game on a pitch, which is shared with the local rugby side, Newport Gwent Dragons, who played at home on Friday night, and carved out an opening when Ollie Banks played a one-two with Gary Roberts on the edge of the area, but his shot went narrowly wide.
O’Shea crashed a volley against the cross bar from the edge of the area and, as the ball bounced out, Gnanduillet failed to convert the rebound with his head.
The Ivorian striker had another sight of goal just before the break after good work by O’Shea on the right but blazed over the bar.
He sent a rasping volley towards goal that Pidgeley was equal to shortly after the interval.
Newport’s keeper had to be on his toes to save well when Banks slotted in Ryan. Ryan’s next burst in to the box paid dividends.
O’Shea’s cross caught the attention of Gnanduillet who challenged keeper and defenders.
The ball broke for Ryan to tuck in to an empty net.
Gnanduillet squandered a one-on-one and Newport would make the Spireites pay soon after with Chapman’s penalty kick.
Newport had their tails up and put the game beyond Chesterfield when substitute Sandell was first to react after Lee had saved well from Washington.
Richards, who had replaced Banks, gave the visitors a lifeline when he pounced from inside the six-yard box in stoppage time but it was too little, too late for the Spireites.
Spireites (4-2-3-1): Lee 6; Talbot 6, Evatt 7 (c), Cooper 5, McFadzean 6; Ryan 8, Hird 6; O’Shea 7 (Doyle 78), Banks 6 (Richards 75); Roberts 6 (McSheffrey 80); Gnanduillet 5. Subs: Chapman, Togwell, Devitt.
Newport (3-4-3): Pidgeley 6 (c); Worley 6, Oshilaja 7, Hughes 6; Jackson 7, Chapman 7, Naylor 7 (Flynn 88), Willmott 7; Jolley 7 (Sandell 80), Crow 7 (Minshall 60), Washington 7. Subs: Stephens, Pipe, Jones, Barker.
Goals: Crow 6, Chapman 75, Sandell 87 (Newport; Ryan 62, Richards 90+1(Chesterfield).
Bookings: Banks, Jolley.