Match gallery: Chesterfield 1 Crawley Town 2
The Spireites were doing all the late pressing with the game locked at 1-1, before a mistake and a quick counter attack allowed Lewis Young to grab a stoppage time winner for Crawley.
Town slip back into the bottom two on the strength of the result, having climbed as high as 21st during the match - which they led from the 18th minute.
Louis Reed’s goal was cancelled out by the impressive Karlan Grant after the interval and a draw might have been a fair result before the late drama.