Washington’s defence had conceded only three goals in their opening three league games.
But they leaked five to impressive Shildon in Saturday’s Emirates FA Cup first qualifying round tie.
Experienced striker Paul Connor slotted home past Mechanics goalkeeper Dale Connor with only nine minutes gone at the Nissan Sports Complex and, by the 38th minute, Steve Hutchinson’s men were chasing the game.
Former Blackpool skipper David Ferguson bagged a well-taken brace to make it 3-0 for the Railwaymen in front of a 157-strong crowd.
Ash Davis quickly reduced the deficit with a magnificent, low 20-yarder beyond the dive of keeper Nick Liversedge, but Shildon still reached half-time with a three-goal cushion courtesy of a second goal from Connor, expertly chipping into the corner of the net.
Joe Walton temporarily raised the hopes of Washington, after they upped the tempo at the start of the second half, but Connor sealed Shildon’s victory as he completed a hat-trick.
In addition to Shildon, three other Northern League teams are definitely through to the next stage.
Consett played particularly well to defeat struggling Harrogate RA 5-0 away, with strikes by Charlie Clamp (og), Luke Sullivan (2), Jordan Nellis and Josh Gray.
Bishop Auckland also scored five times and visitors Ossett Albion managed only one at Heritage Park.
Andrew Johnson (2), Ian Ward (2) and Chris Winn were the matchwinners.
Morpeth Town also defeated opposition from outside the Northern League, and their 4-2 victory over Colwyn Bay was easier than the score line suggests.
Michael Chilton and Paul Robinson had them comfortable. Even after Adam Whitlock halved the arrears, Morpeth were untroubled and went 4-1 up through Chris Reid and Robinson.
The game was into the last minute when Gary Burnett claimed a second goal for the visitors.
Two teams live to fight another day and will replay tomorrow night.
Sam Garvie scored both Billingham Synthonia’s goals in the 2-2 home draw with Ossett Albion, and Liam Thear and Malcolm Morien earned Dunston UTS a second chance against Skelmersdale United.
Marske United, beaten 2-0 by Marine and Newcastle Benfield, who went down by a similar margin to Bridlington Town, are out of the money-spinning competition.
Spennymoor Town progressed with a thrilling 5-3 success at Radcliffe Borough.
Goalkeeper Daniel Lowson’s incredible Moors opener from his own box was levelled by Elliot Rokka a minute into the second half.
Joe Tait and Nathan Fisher fired Moor 3-1 up before Jack Hindle cut the deficit. James Curtis and Andrew Johnson then steered Jason Ainsley’s side into a 5-2 advantage, before Aboubacar Sanogo grabbed a third for the Lancashire side.
Blyth Spartans won through 3-1 at home to Frickley Athletic.
Sean Reid scored twice in five second-half-minutes to lift the Croft Park side. Though Nathan Curtis replied on 81 minutes, Dan Maguire sealed Blyth’s win a minute from time to delight the majority of a 667 crowd.