Danny Nicholls rang the changes bringing in a new strike partnership of Gavin Jaggard and Gary Crawshaw, as well as Dean Powles into midfield and Daniel Mead back at full-back.
The Ducks set the tone early on, and could have taken the lead in the fifth minute. The lively Crawshaw latched onto a through ball, beating the offside trap to leave himself one-on-one with Lee Carroll. The goalkeeper read the Crawshaw's effort well though, saving his low effort with his legs.
Two minutes later another chance fell to United. Greg Williams' deep cross from the right picked out Powles, but the midfielder's guided header was superbly tipped away by Carroll. An outstanding save.
It truly was one way traffic in the opening stages. On fifteen minutes Jaggard took Mead's left-footed cross on his chest, but could only direct a left-footed effort over the bar.
Northwood then gave Aylesbury a scare, springing their first attack of the game. Peter Dean did well to retrieve a seemingly lost cause at the byline, and he played the ball in for the in-rushing Chris Gell who shot over the bar.
The Ducks did have the ball in the net twice before the interval, unfortunately on both occasions the linesman on the near touchline had already raised his flag, Crawshaw and Edgeworth the non-scorers.
Crawshaw was denied again, this time by a fantastic saving tackle by Luke Evans, having been played in by Paul Edgeworth. Edgeworth himself then headed over, right on half-time, after Liam Dolman had delivered an excellent cross.
Half-time: Northwood 0-0 Aylesbury
The second half started in much the same vein, Aylesbury creating the chances but being kept at bay, although Northwood had more of a say in proceedings after the break.
Crawshaw held up the ball well early on, laying in Mead down the left. His cross came all the way through to Greg Williams, who had to adjust quickly and his volley subsequently flew over the target.
A goal-kick then found its way through to Crawshaw, but his left-footed effort went over. Danny Nicholls then swapped Greg Williams for Roni Joe in an attempt to give a more attacking edge to Aylesbury's play.
Northwood were then forced to make a change, earlier hero Carroll replaced between the sticks by Dean Lindsay.
Crawshaw went close again, this time shooting wide on the turn after the ball had been passed to him inside the area by Roni Joe.
The game was now a more even affair, both sides having a share of chances. Debutant Fraser Toms shot well over at one end before Jonathan Bewers nearly broke the deadlock for Aylesbury. After seeing his first effort blocked, his second shot from 20-yards was superbly saved by Lindsay.
The following corner was even closer to bringing a goal. The ball was headed back into the danger area by Liam Folds, and Jaggard pounced. The ensuing melee saw the ball bounce around just feet from the goal-line, rebounding off keeper and defender before finally being gathered safely by Lindsay.
After Another Aylesbury corner was headed over by Kamran Abassi, Jack Rashid made his first true save of the match, forced to tip over Darren Grieves' header from another corner kick.
Northwood had the best chances to snatch a win late on. Firstly they couldn't capitalise on from a goalmouth scramble, then Peter Dean fired wide when well placed and with the goal gaping.
With two minutes remaining Edgeworth tried his luck from distance, but the shot hit a defender and looped into the box. Dean Powles was apparently clattered in the area when challenging for the loose ball, and amidst mild penalty appeals Daniel Mead fired the rebound over the bar.
In injury time Darren Grieves missed the best chance of the game, and a chance to grab an underserved win for Northwood. Thankfully for United he shot over after he had been picked out with a cross, and the tie ended 0-0 with a replay beckoning.