Shaun Miller scored his 16th goal of the season to boost the Railwaymen's play-off push with a 1-0 victory which extended Southend's winless run to five games.
Crewe had the best of the chances in a dire match. Dave Artell headed the ball against the crossbar from Danny Blanchett's corner before he nodded a free-kick straight at Southend goalkeeper Glen Morris.
Lee Bell shaved the crossbar with a free-kick from the edge of the box and Clayton Donaldson should have done better than fire wide when cutting inside following a strong run.
The Shrimps offered little in attack all game, but Barry Corr looked odds on to tuck away Lee Sawyer's centre before Artell made a vital last-ditch tackle.
The visitors had to wait until the hour mark before they had their first shot on target, Ryan Hall's 20-yard effort forcing Ryan Taylor into a full-stretch save.
But the Railwaymen took the lead in the 75th minute when Morris saved Donaldson's initial shot and Miller hooked the rebound home.
Donaldson almost made it 2-0 when he raced onto Graham Coughlan's under-hit headed backpass, but his lob over the goalkeeper came back off the crossbar.
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