Ello calls for promotion response ahead of busy Easter
Report by Dave Bettley with pictures from Ben Jackson
Linnets manager Michael Ellison urged his players not to let one result derail their season after Linnets succumbed miserably to the leaders at APEC Taxis Stadium.
With second-placed Avro losing at home to Bootle, Bury went four points clear in Pitching In Northern Premier League West after a victory which was done and dusted in 26 minutes.
The Shakers had by that time surged into a three-goal lead - a position from which there was no way back for the shellshocked hosts in front of the sell-out crowd just short of 1,600.
Runcorn avoided a drubbing by holding the Shakers at bay in the second half, but Ellison admitted that the visitors hadn't been forced to work hard for the points.
Bury are the first team to do the double over Linnets this season.
Runcorn's woes were compounded with the late dismissal of skipper Jacques Welsh for a second bookable offence.
He will now miss Easter Monday's home game against former club Bootle as Linnets look to continue a promotion push through the play-offs with title chances all but over.
They trail Bury by eight points with five games to play and the Shakers also ahead on goal difference.
Runcorn's next game is at Trafford on Good Friday and Ellison says a big response is needed over the Bank Holiday weekend to ensure that Saturday's defeat doesn't ruin a promising campaign.
The boss admitted he was partly culpable for the disastrous spell, which had seen Linnets concede three times in 16 minutes.
With hindsight, he felt he had got Runcorn's defensive set-up wrong in this first home defeat of his second spell in charge.
Ellison also believed the absence from midfield of the experienced Steve Irwin had been very costly.
This prompted changes to the line-up with Harry McGee and James Steele being recalled.
Steele's inclusion saw Naim Arsan come off the wing into central midfield with Dec McLoughlin relegated to the bench.
With a fierce wind in their favour in a first half, which would see tough conditions further deteriorate in the rain, Runcorn made a bright start.
Early pressure brought a string of free-kicks and corners, whipped in dangerously by Matty Rain.
However, Bury were moving the ball quickly in possession and the hosts soon began to struggle with the away side's speed of thought.
The title favourites took the lead in the tenth minute. Rustam Stepans, whose goal had separated the teams at Gigg Lane in September, drilled in a cross from the left for Jordan Lazenbury to scramble the ball home.
An offside flag was raised on the far side but after consulting with the assistant, referee Sam Parnaby overruled the offside call and allowed the goal to stand.
The Shakers doubled their lead in the 21st minute as an almighty mix-up between right back Joe Ferguson and Welsh on his inside saw neither deal with a through ball.
Bury striker Mo Touray seized on the opportunity with a subtle finish inside the left post.
The contest was effectively over five minutes later, when Stepans caused Runcorn further problems on their right.
He played in new signing Tom Carr to this time deliver low into the six-yard box.
Touray and attacking full back Bebeto Gomez were waiting for it, the latter getting the vital touch at close range.
Half-time substitutions of McGee and a limping Scott Bakkor enabled Ellison to switch to a back five but it was an exercise in damage limitation more than anything.
The changes stabilised Runcorn but Bury were comfortable on their convincing lead.
They posed less of a threat but had already done the job.
It was 73 minutes before Shakers 'keeper Mitch Allen was called into action, clawing a shot from 16-year-old sub Noah Roberts from under his crossbar.
Runcorn recycled the ball, but their follow-up attempts was blocked.
Welsh, meanwhile, had been walking a tightrope since being booked in the sixth minute for a rash challenge on Touray.
It finally snapped as a second yellow in the 88th minute, also for a foul, left Runcorn to complete a bleak afternoon with 10 players.
Runcorn Linnets: Yusuf Mersin, Joe Ferguson, Matty Rain (Declan McLoughlin, 83 mins), Jacques Welsh, Peter Wylie, Lewis Doyle (Isaac Graham, 85 mins), Naim Arsan (Noah Roberts, 61 mins), Harry McGee (Markell Foulds 46 mins), Scott Bakkor (Sean Miller, 46 mins), James Steele, Ryan Brooke.
Attendance: 1,570.