FEW games witness such a turn around in fortunes as this clash in deepest Buckinghamshire - a transformation that was all to WGC's detriment.
In an impressive first-half display, Adam Fisher's side mostly eradicated the memories of their poor home showing against Broxbourne three days earlier. They gave a sound defensive performance, more than deservedly led 1-0, a lead that should have been doubled or even trebled.
But if Fisher's half-time message was "same again boys'' in the second-half, then his Holmer Green counterpart Chris Allen's talk had much the more desired affect, as a home team who had hardly offered a threat in the first 45 minutes, tore WGC apart in the opening quarter of the second period to lead 3-1 on the hour.
Fisher fielded new keeper Grant Beckwith for his debut, Joe Croft having damaged his hand in the 4-3 home defeat to Broxbourne in midweek. Other than that, the GC line-up was unchanged, as they were still without injured central defenders Carl Mensah (foot) and John McGrandles (hamstring).
It all began well for WGC, taking a 12th minute lead, Yasin Boodhoo sweeping a fine ball out to Dave Parkinson, who in turn, played an accurate pass into the path of Josh Bronti, who took it on to beat home keeper Sam Butcher for his seventh goal in four games.
The Citizens dominated the opening 45 minutes and closed the half with a quartet of near misses that should have doubled their lead.
Firstly, Jay Welsh swung in a free-kick that found namesake Jay Lovell on the back post, but he shot across the face of the Holmer Green goal. Then Parkinson raced through to stab it past keeper Butcher and the post by inches.
Parkinson cut inside to drive another shot for the corner, that the keeper turned around at full length and the half closed with a Welsh header shaving the far post by inches.
But within three minutes of the start of the second period, Holmer Green were level, winger Joe Collins getting behind the WGC defence to stoop low and head a Curtis Stone free-kick past Beckwith, who to this point, hadn't had a save to make.
Six minutes later, the home side's top scorer Dean Allen showed greater determination than the new WGC keeper to reach a Luke Graham cross and forced the ball home for 2-1.
Five minutes later, it was 3-1, as again overlapping full-back Graham put in a high ball and home forward Dean Powles netted a simple goal, when it was slipped square to him.
Two minutes later it was almost four in the most remarkable of turnarounds, as Collins' cross was stabbed by Powles past Beckwith against a post, the ball rebounding back into the arms of the relieved and beleagued keeper.
On 65 minutes, WGC came within a whisker of getting back into the game with a second goal, Bronti setting up Nathan Dimmock who drove a powerful shot past Butcher, only to see full-back Graham complete a remarkable clearance off his goalline, clearing over his own crossbar. A goal then and the Citizens might have been right back in it.
Instead, with 10 minutes left, the WGC defence was cut open again, Elliott Derby broke clear, outstripped Boodhoo and set up Allen for his second, simple goal for 4-1.
In the final five minutes, WGC staged an unlikely revival. Jason Caswell, who had a quiet game, collected 25 yards out, waltzed around a couple of challenges and drove in a fine solo goal for 4-2.
On the stroke of full-time, a high ball to the left, saw Welsh do well to hook it back into the area and Caswell came in to stab home his second in four minutes for 4-3, but with only stoppage time remaining.
In the four minutes overtime played by referee Snuggs, Holmer Green broke away again. Allen brought a diving save from Beckwith, who tipped the striker's shot away, but only to substitute Ryan Willmott who drove in the rebound to complete the afternoon's scoring.
WGC: Beckwith, Perrin (Smith 63), Lovell, Boodhoo, Welsh, Cifuentes (Cato 63), Dimmock, Arnott, Bronti, Caswell, Parkinson (Gunn 63).