Chesterfield assistant boss Tommy Wright felt his side only had themselves to blame for the 2-1 defeat at Carlisle.
The Spireites went ahead through Drew Talbot but Ben Parker equalised in the second half and Francois Zoko's 10th goal of the season six minutes from time eventually secured the points for the hosts.
"We switched off and paid the price. We needed that second goal and we were disappointed because it was a vital game for us," said Wright.
"I thought we were in control and the better side in the first half when we moved the ball well and we continued to be dangerous after the break.
"Poor marking and discipline cost us. We have only ourselves to blame. We should be leaving Brunton Park with at least a point."