Sadly the whole game was overshadowed in the 19th minute when Gregor Robertson and Tom Taiwo went in for a 50-50 challenge, Spireites defender Robertson breaking his leg in the incident, play being halted for eight minutes while the Chesterfield man was treated and then stretchered from the pitch, Darren Currie coming on in his place.
With 28 minutes gone Matty Robson should have done better for the visitors when he headed a Hurst cross over the top from close range. Anyinsah then having a shot deflected wide, Harte then seeing his volley from the resultant corner well blocked. Hurst then somehow spooning the ball over from almost under the crossbar when Robson had stuck a low delivery in. Anyinsah then having a shot closed down moments later before he smacked the rebound wide.
Chesterfield came back as the half ran out though and Lester had a shot saved by Adam Collin in the 43rd minute before in the first few seconds of nine minutes added on time they took the lead from the penalty spot. Currie firing home after Taiwo had brought down Boden in the box. The Spireites then going close again before the whistle when Lester had his header parried away by Collin.
Lester then almost doubling the lead once more for the home side six minutes after the interval when he made a good run forward before seeing his 18-yard shot well saved by Collin. In a busy spell in the game Lee then made an easy stop from Adam Clayton's shot for Carlisle before Collin made a block on Drew Talbot's header. Chesterfield then going even closer when Collin tipped an Ian Breckin header onto the underside of the crossbar.
United came out of their shell on 62 minutes though when they equalised against the run of play, Robson nodding home at the back-post from Taiwo's deep cross in from the right. The Cumbrians then shocking the home side by making it 2-1 seven minutes later when substitute Peter Murphy thumped a header past Lee from a Carlisle corner.
An excellent crisp passing move forward on the break from the Blues then saw them close out the tie as they made it 3-1 on 78 minutes. Marc Bridge-Wilkinson, Richard Offiong, Robson and Anyinsah all involved in setting up play for Clayton, the Manchester-City loanee then registering his first goal in professional football with a tidy finish from just inside the box.
Anyinsah and Taiwo then both shooting narrowly wide in the closing stages as the Cumbrians saw out the game strongly. Lee having to make a good save in the 90th minute to stop the final scoreline from reaching 4-1 when Bridge-Wilkinson shot goalwards from Offiong's pass. Carlisle eventually progressing easily to the northern final four, albeit after a big scare from the League Two Spireites.