Chesterfield came from behind and a man down to see off a Notts County side who’d taken the lead when Karl Hawley scored towards the end of the first half to keep their Wembley dreams alive.
Spireites had lost Lee Johnson midway through the first half when he controversially received a straight red for a foul on Alan Judge.
Two goals in four minutes from Mark Randall and Dean Morgan were followed by a Jordan Bowery close range header from Spireites ninth corner, at the time County had earned just one.
Manager had John Sheridan selected a team that showed five changes from the one that lost at home to Colchester.
In came Aaron Downes, Bowery, Morgan, Randall and, for a rare start, Craig Clay. Midfielder Derek Niven was on the bench after recovering from an ankle injury, alongside former Magpie Craig Westcarr.
Spireites had the vast majority of play in the first half but turned round a goal and a man down.
Bowery, Morgan and Clay almost pierced the Notts back line before Mike Edwards picked up an injury and was replaced, as was fellow centre back Krystian Pearce as Martin Allen completely re-jigged what was now a much weakened line up.
Midway through the half, Chesterfield were down to ten. Johnson stretched his foot for a high ball and caught Judge on the head. It was a clear foul, but a red card was a surprise. Morgan subsequently moved from a five man midfield to join Bowery up front.
Ravenhill forced a snap shot from Greg Fleming and a Judge cross just eluded Spicer as County stepped things up. Randall, Morgan and Bowery all had efforts blocked before Hawley, in too much space, tried one from 25 yards and his effort seemed to catch Fleming off guard and the ball flew in. The scorer drilled one just too high a couple of minutes later.
After the restart Bowery’s angled shot from a Clay pass slipped under Nelson but he got enough on it to prevent it from reaching the target. Morgan and Randall had on target long rangers blocked and Downes volleyed over from a corner as Spireites refused to give in.
Fleming blocked a Demontagnac distance effort in a rare Notts raid before Randall hammered in his first goal for the club, a fine shot from 25 yards after a Grounds cross had only been partially cleared.
The visitors were soon ahead. Randall threaded the ball through for Morgan who teased his marker before left footing in low to the far corner. Nelson spilled a Clay free kick and Morgan almost pounced as the visitors refused to shut up shop and from a short corner, Morgan crossed in for Bowery to head home to clinch the tie.
NOTTS COUNTY: Nelson 6; Allen 6, Edwards 5 (Sodje 16/ 6), Pearce 5 (Thompson 16 / 5), Harley 8; Bencherif 6, Spicer 6 (Hughes 68), Ravenhill 6, Judge 6; Demontagnac 6, Hawley 7. Subs (not used): Speiss, Clarke.
CHESTERFIELD: Fleming 5; Talbot 7, Holden 6, Downes 7, Grounds 6; Mendy 7, Johnson 5, Clay 7 (Darikwa 90+2), Randall 8, Morgan 7(Boden 87); Bowery 6 (Westcarr 85). Subs (not used): Smith, Niven.
Goals: Hawley 43 (Notts), Randall 64, Morgan 68, Bowery 77 (Chesterfield).
Referee: David Webb (County Durham).
Bookings: Holden (Chesterfield), Demontagnac (Notts).
Sent Off: Johnson (Chesterfield).