A mistake from young goalkeeper Chris Lewington proved decisive as John Still's strugglers dropped back into the relegation zone with a third consecutive defeat at The Alexandra Stadium on Saturday.
Abu Ogogo's back-pass, with the match finely poised at 1-1 nineteen minutes from time, should have not have posed too many problems for Lewington but the ball somehow bobbled over his foot and trickled agonisingly over the line.
'The mistake has cost us,' said assistant manager Terry Harris, 'But these things happen. Maybe Chris should have taken another touch, but he's a young lad and will learn from it.'
Yet things had started so well for the Daggers. Brian Woodall, back in the side following a groin injury, had fired them in front after just 16 minutes as they looked for the victory they need to ease their relegation worries.
Still's side, with a 100% league record against the Railwaymen, showed two changes from the FA Cup defeat at Millwall in midweek - on-loan West Ham striker Cristian Montano and Woodall replacing Richard Rose and DJ Green - but it was the hosts who started the brighter.
Luke Murphy and Nick Powell both tried their luck from long range in the early stages, but it was the Daggers who struck first. Woodall charged down an attempted clearance from home captain David Artell out on the left before coolly slotting past goalkeeper Steve Phillips from a tight angle.
The hosts were almost level straight from the restart, when Murphy fired wide from a good position, but it was Still's side who threatened a second soon after. Montano and Femi Ilesanmi combined well down the left to create an opening for Dominic Green, but the winger was denied by a fine save from Phillips.
Lewington was then called into action to push out an effort from Powell just past the half-hour mark, while the young Crewe striker, who was voted Player of the Month for December, was again denied by the Daggers keeper moments later.
But the hosts were level three minutes before the break. Artell made up for his earlier error by chesting a cross from Jamie Lowry into the path of Greg Pearson, and the Burton loanee sent a half-volley past Lewington from 18 yards - his second goal in consecutive matches.
Crewewere close to going in front soon after the resumption when a Pearson header beat Lewington, but Green was in the right place to clear the effort off his own goal-line. Meanwhile, at the other end, Montano was denied by Phillips following a swift Daggers counter-attack.
However, the game turned on Lewington's 71st minute howler. Ogogo did well to dispossess Powell before rolling the ball back to his goalkeeper. But Lewington completely missed his kick and the ball trickled over the line to give Crewe an unexpected lead.
The Daggers responded well to that setback and enjoyed their best spell of the match. Substitute Adam Cunnington, who had replaced Woodall, brought the best out of Phillips before Harry Davis completed the clearance, while Jon Nurse then looked odds-on to equalise 15 minutes from time. Robbing Phillips inside the home penalty area, the Barbadian's shot on the turn was heading into the net until the intervention of Matt Tootle, who deflected his effort over the crossbar.
Substitute Eoin Wearen then volleyed straight at Phillips, before Nurse fired wide from 10 yards following a goalmouth scramble, as the Still's men began to crank up the pressure.
But the Railwayman sealed the points seven minutes from time. The Daggers felt the ball had gone out for a throw on the near side, but referee Jeremy Simpson penalised West Ham loanee Ahmed Abdullah instead, and Lowry's free kick was headed home by Adam Dugdale at the far post.
Powell than completed the scoring three minutes later with a lovely chip over Lewington, after Crewe substitute Ajay Leith-Smith had been dispossessed by Scott Doe inside the penalty area.
'The ball had gone out for their third goal,' said a disappointed Harris, 'But the linesman missed it, they score and then we collapse. But we're staying positive. We gave a good account of ourselves and their keeper had more saves to make than ours. We just need to put this behind us and move on to the next game.'
Attendance; 3,282 (126 away)