Chesterfield raised their hopes of avoiding relegation when they thumped QPR 4-2 at Saltergate to dent the London club's automatic promotion hopes.
Although Tony Thorpe gave the visitors an early lead, Chesterfield turned in one of their best displays of the season to completely overwhelm Rangers.
At the end, Rangers boss Ian Holloway had to admit: "Some of our decisions and some of our marking at set pieces and corners was an absolute joke.
"I cannot protect the team after a performance like that. It was absolutely diabolical." Chesterfield's assistant manager Lee Richardson, said: "That was probably our best performance this season.
"Coming from a goal down is never easy against anyone but it is particularly difficult against a team like QPR." On this performance, it was hard to tell which side was at the top and which was at the bottom. Chesterfield showed energy and invention to unhinge a Rangers team that never looked comfortable even after Thorpe pounced.
His 11th minute finish was expertly taken but from then on Chesterfield asked the questions.
Rangers had few answers and they were caught on the break when Glynn Hurst struck a post and the impressive Jamie McMaster finished well from the edge of the area to convert the rebound.
The young Leeds United midfielder was involved in most of Chesterfield's best moves, but it was a corner that saw Ian Evatt head in from an unmarked position at the back post.
Rangers did respond when Steve Palmer smashed a right foot shot from 25 yards into the top right hand corner in the 62nd minute but three minutes later, Chesterfield were back in front.
A well taken free-kick from the left was glanced inside the left hand post by Hurst and Rangers never looked like recovering after that.
The goal which finished them off was well taken but it came from a sloppy piece of defending.
A poor clearance set up midfielder Mark Hudson and, from 20 yards out in a central position, he lashed a low left foot shot into the bottom right hand corner to complete a memorable day for Chesterfield and a dreadful one for Rangers.