Rochdale scored two late goals to snatch a 2-2 draw in a dramatic late comeback that denied Chesterfield what looked a certain victory in the driving rain at the Proact Stadium.
A goal in each half from Gary Roberts and Marc Richards put Chesterfield in control but Ian Henderson converted a penalty after Richards was sent off for handball and Peter Vincenti headed home in the second minute of stoppage time.
Rochdale had an early chance when Scott Hogan crossed from the left in the 11th minute but Henderson's downward header was pushed away by Tommy Lee diving to his left.
Chesterfield looked more threatening and after Richards sliced wide from 10 yards in the 37th minute, the striker was involved in the opening goal two minutes later.
Richards played the ball to Jay O'Shea who fed it through to Roberts who slipped a low shot past Josh Lillis from 10 yards he played a part in the second in the 69th minute.
Ollie Banks struck a post and Nathan Smith's follow-up was blocked on the line but Roberts helped the ball across to Richards who forced the ball home but Rochdale hit back.
Referee Andy D'Urso ruled Richards had blocked a goal-bound shot with his arm and Henderson smashed the ball into the roof of the net before Vincenti rose unchallenged to head in a corner.