Chris Porter scored twice as Crewe went on the rampage in a 5-1 defeat of a desperate Chesterfield side in League Two.It looked ominous for the Spirietes as early as the sixth minute at Gresty Road when Porter took his tally for the season to five as he drove past Tommy Lee.Chesterfield's Chris O'Grady volleyed over when well placed and Matthew Briggs skied a presentable far-post chance on the stroke of half-time.But the game was out of reach of Gary Caldwell's men soon after the break with Crewe adding two inside seven minutes. Porter swept into the far corner after being released by Ryan Wintle after 47 minutes and young defender Perry Ng scored his first goal for the club seven minutes later.A poor throw by goalkeeper Lee was intercepted and Ng strode into the box and drove home. Cooper added a fourth in the 66th minute when he turned his man and picked his spot.Chesterfield grabbed a consolation when Kristian Dennis' shot came back off the bar and hit defender Eddie Nolan before rolling into the net with 18 minutes to go.But substitute Callum Ainley rounded off the rout as he finished off from close range with nine minutes to go after Jordan Bowery's effort was parried by Lee.