Jon Meades powered home a fantastic header in stoppage time to make round one well and truly AFC Wimbledon's.
The 191 travelling fans were the ones singing in the rain as they greeted their hero who slid all across the sodden turf to take the applause.
Jake Reeves's centre was met by the defender just when it looked as if both sides had settled for a point and all 90 minutes plus, because at one stage it looked as if the deluge would drown the game.
There was a biblical flood battering Bury in the first half, but Dons had their prayers answered when Lyle Taylor leapt like the proverbial salmon to cancel out an undeserved Shakers lead.
Paul Robinson made the minimal contact with James Vaughan to give away the penalty clinically dispatched by Neil Danns on 26 minutes.
It was all the more ironic after Vaughan had tried to make Barry Fuller part of the touchline hoarding with a bruising tackle but escaped a yellow card.
However, Andy Barcham twisted his way down the left and delivered the perfect ball for Taylor to head back past Ben Williams and in for 1-1 at the break.
Dean Parrett wavered for just a split second when through straight after the restart, and the chance was snuffed out by a decent tackle from Niall Maher.
James Shea relieved to see a brilliant curling effort from Danny Mayor flash just over the bar, before Andrew Tutte earned a yellow to earn Dons a bit of relief as he charged in on Jon Meades, with Bury fighting back
James Shea denied Danny Mayer, and in what is certainly the first of three games in a month against Bury, it could be four with an FA Cup replay, Dons have struck first blood.
191 away fans