In a thrilling meeting between the very familiar Portsmouth-based Wessex Premier rivals, Quirke fired home after a fine pass from Tom Dinsmore on 92 minutes to ensure it finished 3-3.
Moneyfields had mounted a superb earlier fightback and looked destined for the three points after coming back from two goals down to lead 3-2 heading into injury-time.
However, Turnbull, who guided US Portsmouth to the FA Vase semi-finals last term before moving to Dover Road, and his squad full of former USP players were forced to settle for a point on a night of high drama.
The hosts, now managed by Tom Grice, were sure to be fired up in a bid to get one over on their former boss Turnbull and several old team-mates.
And they made the perfect start with two strikes in the space of five first-half minutes from Tom Dinsmore and Vinnie McGee handing them a two-goal lead inside 16 minutes.
After right wing-back for the night Joe Briggs was brought down in the area, another ex-USP man, Dec Seiden, kept his cool to fire home the resulting penalty and pull Moneys level on the half-hour mark.
The remarkable turnaround was completed with US Portsmouth's top scorer from each of the previous two seasons James Franklyn making it 3-2 just 10 minutes after the restart.
Just when it looked as though Turnbull would complete the league double over his former employers in his first season since moving on from the club, US Portsmouth had the last laugh.
Quirke struck in injury-time to leave Moneyfields forced to settle for a point and a number of USP's former players disappointed on their first return to the Victory Stadium since an incredible run to the FA Vase last-four last term.