Sheffield Wednesday manager Chris Turner accused his players of failing to take responsibility after they were well beaten by a Chesterfield side who boosted their survival chances.
Two goals by Glynn Hurst and a stunning volley by Chris Brandon deservedly gave the Spireites the points, while the Owls could only muster a single goal from Guylain Ndumbu-Nsungu.
Turner was angry with the performance and said: "The disappointing factor for me is that certain players did not take responsibility on the field." For Chesterfield boss Roy McFarland the result was a huge lift that moved his team out of the bottom four.
He said: "We were compact as a team and now we have to do that away from home." Wednesday had plenty of the ball in the first half but created little and were punished for sloppy defending on the stroke of half-time when Hurst finished well from ten yards after the ball deflected off Leigh Bromby.
The visitors' defence went to sleep again in the 59th minute when Hurst stole in to lob Ola Tidman from 12 yards and the home side had a great chance to finish it five minutes later when Mark Hudson put the ball wide from six yards.
The Owls gave themselves hope when Ndumbu-Nsungu surged through the middle to finish with a low left-foot shot from 12 yards, but Brandon's volley from near the left-hand touchline in the 75th minute settled the contest.
Ndumbu-Nsungu was denied a second by a super save by Carl Muggleton in the 84th minute, but the match ended on a note of shame for the Yorkshire club when Alan Quinn was sent off for raising his arm at Gareth Davies.
It was a moment of madness and Turner said: "Certain players have to look at themselves and say are they doing the right things."