The Spireites sealed Checkatrade Trophy progression with a 2-0 win over Crewe Alexandra at a cold and rain-sodden Gresty Road.Jay O'Shea grabbed his second cup goal of the week to give the visitors a first-half advantage and Connor Dimaio sealed his side's passage to the knock-out stage with a second half penalty.
After half chances had been fired over, one for each side from George Cooper and O'Shea, the Spireites man went even closer with his second effort to open the scoring. After an initial visiting freekick had been cleared, the ball was played wide to Reece Mitchell, with the former Chelsea man feeding inside to O'Shea, whose 22-yard strike was true and too strongly-driven for Alex 'keeper Ben Garratt to get close to.
Growing in confidence, Kristian Dennis was within a whisker of stabbing home a Rai Simons centre for a second before Gboly Ariyibi improvised from a short corner, nearly catching the 'keeper out as the ball landed on the roof of the net.
Substitute Callum Saunders, son of former CFC manager Dean, went close as he bundled wide at the back post following a cross, while Lloyd Allinson made a comfortable save from a low Zoumana Bakayogo shot inside the area.
Crewe finished the half strongly, but a well-marshalled back three kept the hosts at bay - with the Spireites heading through to the knock-out stages the way things stood at the break.
Dennis had the first attempt of the second period as his 24-yard freekick was stopped by an Alex boot, before Mitchell won back possession, ran at the last defender but was unable to find a team-mate with his pull-back.
Incoming Spireites teenager Ify Ofoegbu received an instant yellow for a foul after his arrival and Ben Nugent should have done better from the resulting freekick as he wastefully headed over.
An inviting inswinging freekick was close for the hosts, but the men attacking the Spireites' area were unable to get a touch between them as the ball flashed wide.
Allinson's misjudgement almost opened the door for Alex as Ainley scampered to keep the ball in, his squared ball rolled across the goal line, but Tom Anderson was able to clean up. Breaking quickly, substitute Ricky German was soon running towards the Crewe goal, he managed to shoot low, but Garratt comfortably saved.
The home pressure was building, but a sweepoing Ariyibi ball found German and heading into the area the young striker was felled for a visiting penalty kick. Dimaio took the responsibilty and drove home to make things more comfortable for the Spireites.
The away side's second knocked the life out of the hosts, with the Spireites safely through to the EFL Trophy knock-out stages thanks to their second group-stage win.
Elsewhere, Wolverhampton Wanderers under 21s beat Accrington Stanley 4-0, meaning the Spireites go through second in the group and face an away tie against a northern group winner in the second round, with teh draw to be held on Thursday.
Crewe Alexandra: Garratt (gk) - Davis, Nugent, Lowe (c) (Saunders 16'), Cooper, Bakayogo, Hollands (Kirk 78'), Udoh (Finney 64'), Kiwomya, Ng, Ainley
Subs not used: Richards, Guthrie, Wintle, Lowery
Chesterfield: Allinson (gk) - Evatt (c), Anderson, Maguire - Mitchell, Dimaio, O'Shea (German 64'), Nolan, Ariyibi - Simons (Ofoegbu 64'), Dennis (Humphreys 78')
Subs not used: Parkin (gk), Liddle, Evans, Donohue
Chesterfield: O'Shea 23', Dimaio 81' (pen)
Attendance: 929 (74 Spireites fans)