The game started positively enough for United, as Drew Roberts superbly picked out Daniel Mead with a right-wing cross, and the slightly built wide-man saw his shot well saved.
But with just three minutes on the clock the struggling Western Division side took a shock lead. Aylesbury found themselves wide open on the counter-attack, and the ball was well worked to Gavin Smith who calmly slotted past debutant keeper Liam Little. 1-0 Bracknell
Greg Williams came close to levelling minutes later, firing a long-range shot just wide after the ball dropped to him for a corner. Bracknell could have doubled their lead, but Jon Palmer couldn't get hold of his volley having had the ball crossed to him, and Neil Baker also shot wide.
The Ducks nearly found an equaliser through the unlikely form of a Matt Hayward half-volley. The veteran defender latched onto a Mead cross, showed some neat chest control, but lashed his shot wide of the far-post.
Roberts had a near-post effort well saved by Poyser having been fed by substitute Gavin Jaggard, and Palmer hit a dipping effort over the crossbar for Bracknell. Just before half-time Gavin Smith went close with a curling effort that went just over.
Half-time: Aylesbury 0-1 Bracknell
The match turned into a dour affair in the second half, with chances few and far between. Dean Powles had an early shot sail over the bar, and half-time substitute Liam Folds superbly denied Damian Smith with a desperate block.
Greg Williams then went as close as anyone for United on the night, curling a fantastic effort that smacked against the crossbar and rebounded out. Roberts' follow-up effort was then deflected wide.
As the game petered along the Danny Gray popped up to flash a cross-shot narrowly over the bar, having beautifully sidestepped his man.
The game was wrapped up for Bracknell after 78 minutes. Mead's clearance wes closed down, with a suspicion of handball in the process, and worked quickly into the path of Palmer who crashed home a left-footed strike. 2-0 Bracknell
Aylesbury had visibly tired by now and Bracknell's fresh legs of Jody Yee were causing problems. Yee raced clear onto a long-ball rounded Little and squared the ball to the unmarked Danny Hayward. But he could only watch in disbelief as Hayward took an eternity with his shot which was eventually cleared off the line by recovering Aylesbury defenders.
There was to be a third in the last minute of the game, and it went to Yee, who slid in to convert a low cross. 3-0 Bracknell
The home side did have a good spell of posession before the final whistle, culminating in a Drew Roberts shot which was saved by Poyser at his near-post.
Bracknell deserved their win, and as they progress to the fourth round there can be few complaints from Aylesbury, who looked a shadow of the glorious team of the previous Saturday.