The lads followed up their victory over Liverpool on Monday with a fine performance against a subdued United side.
Jon Obika gave us the lead after 35 minutes with a tap-in and the 22-year-old struck more in the second half after Tom Thorpe had brought United level with a spectacular long-range effort.
The three points were well-earned as we kept Warren Joyce's team at bay for long periods of the match and the result cements our position at the top of the Elite Group.
After a cagey opening, Massimo Luongo - impressive as always in midfield - came closest to breaking the deadlock 22 minutes into the match with a fantastic effort from 25-yards that flew inches over the bar.
But it was Obika who made the breakthrough soon after. Fryers' superb low ball in from the left was met by the striker, who swivelled and hammered the ball home from a couple of yards out.
The goal provided the impetus we needed to take the game to United and Obika, who caused problems throughout with his strength and pace, had a couple of efforts well saved by Johnstone.
It felt as though it would take something special for United to get back into the match, and that moment arrived through the boot of Tom Thorpe just after half-time. The 20-year old hit a rising effort from 20-yards into the top left corner that left Jonathan Miles with no chance.
But just two minutes later, we were back in front. Kyle Naughton, playing at centre-back alongside Jake Livermore, looped in a cross from the left which Harry Kane headed onto the crossbar, leaving Obika with the simple task of heading home the rebound from a yard out.
United worked hard to try and force an equaliser but we always looked more likely to add to our lead, with Kane, Obika and Parrett all forcing Johnstone into action.
But he could only keep us out for so long, and we secured the victory in the last minute of the match.
Parrett broke down the left and squared a pass to Obika, who stroked the ball under the goalkeeper and into the corner of the net to secure his hat-trick.
SPURS: Miles; Byrne; Fryers; Livermore; Naughton; Luongo; Parrett; Carroll; Obika; Kane; Ceballos.
SUBS NOT USE: Voss; Stewart; Gallifuoco; Munns.
GOALS: Obika (35, 49 and 90), Thorpe (47).