High flying Crewe kept up their promotion push with an easy win as Chesterfield's miserable run continued.
David Wright put the Railwaymen ahead just after the half hour and his side then missed a host of chances to make the game save before Rodney Jack finally sealed the points five minutes from time.
The home side had begun brightly and Marcus Ebdon forced Crewe keeper Clayton Ince into making a good save with a long-range drive on four minutes.
But the visitors soon began to show their class and should have taken the lead on the quarter hour when Rob Hulse volleyed Kenny Lunt's free-kick over the bar from six yards.
Three minutes later striker partner Steve Jones should have done better but he fired straight at Chesterfield keeper Ben Williams from a tight angle.
Jack missed another chance for Dario Gradi's men before Wright finally opened the scoring with a superb goal.
The full-back coolly slotted past Williams from six yards after Dean Ashton back-heeled the ball into his path on the edge of the area.
Twelve minutes later Chris Brandon had the home side's best chance of the match but his effort was brilliantly tipped over the bar by Ince.
The second half was dominated by Crewe and Ashton, Jack, and Jones were all denied by Chesterfield man of the match Williams.
But five minutes from time Jack finally put the game beyond the Spireites when he placed a shot into the bottom corner after David Vaughan pulled the ball back to him on the penalty spot.
The result keeps Alex in second place behind leaders Wigan but Chesterfield now face being drawn into a relegation dogfight.
After the game Chesterfield assistant manager Lee Richardson said "We're showing plenty of commitment at the moment but our best just wasn't good enough against a very good side.
"We had plenty of possession but never really caused them any problems.
"We have just got to keep our heads and make sure we get enough points to stay in this division. That was our aim at the start of the season." Crewe boss, Dario Gradi said: "Chesterfield is never an easy place to come so it was a very good three points.
"Tactically they caused us problems but never really managed to penetrate our back-line."