The first 45 was a bit on the mediocre side with Park B just about shading the contest.
But, what a cracking second half the large attendance witnessed as both sides really opened up to come at each other at a frantic pace.
Getting the nod for the man of the match performance was Park United B’s James Sheehan who had an excellent first half down the left flank.
Park started with an imposing approach and engineered the first chance of note when Simon Maher flick fed James Sheehan who crossed for Liam Keane to drill narrowly wide from the edge of the box.
A clever disguised ball then from Pearse Celtic’s Stuart Morrissey fell into the path of Keith McCarthy, but the striker just could not get his foot around the ball near goal at a crucial time.
A great ball from Luke Stack looked destined for Liam Keane, but Kelly was alert to the danger and came off his line to clear the danger.
The first goal arrived in the 23rd minute as a result of a superb sequence of play.
After nice improvised play, Liam Keane produced a lovely delicate flick into space which picked out Sheehan down the channel.
The winger looked up before picking out Stephen Fox who drilled home with gusto to give Park the advantage.
Pearse responded immediately with Keith McCarthy playing it on for Stephen O’Leary to fire wide.
This was followed by an excellent delivery from Sean O’Connor which reached the head of Barry Murphy – only to see the midfielder head over while unattended.
Pearse Celtic’s defence failed to deal with Michael Maher’s low cross and when it broke for Stephen Fox, he made Kelly work to save from his low firm effort.
And when Simon Maher set Luke Stack up with a ball that played him in, it took a real top drawer tackle from Stuart Morrissey to prevent Park an opportunity to score a second.
With seconds to the break, Barry Murphy helps on for Gary O’Mahony to drill narrowly wide.
Pearse started well as the second half got under way with Morrissy trying an audacious over-head kick from Craig Roche’s cross.
But, a lovely ball from Liam Keane into the box saw Simon Maher failing to get a vital touch near goal.
Pearse looked persistent now and had a spring to their step when they grabbed the equaliser.
And it came from Stuart Morrissey’s delivery which picked out the head of Barry Murphy who powered home with his thumping header on 53.
Park responded immediately and had the ball in the net only to have it ruled offside by the linesman.
Minutes later; Liam Keane latched on to a through ball, but a superb tackle from Darren Roche aborted the threat.
But, Park restored their advantage again when after Seamus Barrett was tripped inside the box, Liam Keane fired home from the spot to make it 2-1 to Park on 64.
A terrific free kick then reached Stephen Fox, but he just could not get a proper touch and the chance went.
After Seamus Barrett failed with an opportunity from 20 yards out, Pearse Celtic found themselves back in the contest once again when Gary O’Mahony helped on for Stephen O’Leary who threaded one across to Keith McCarthy to squeeze home the equaliser in the 80th minute.
And with minutes remaining, what a save from Eddie Kelly when he stretched to palm away a stinging effort by Seamus Barrett to ensure the contest would go into extra time.
The vital moment then arrived when Seamus Barrett pounced on to a breaking ball to rattle the net with the winner on 95 minutes.
Park United B: Luke Hanna, Paul Seymour, Mark Bane, Kieran Walsh, Eamon O’Connor, Luke Stack, Simon Maher, Michael Walsh, Liam Keane, Stephen Fox and James Sheehan.
Subs: Michael Maher for Michael Walsh (20), Seamus Barrett for Luke Stack (55), Jesse Graham for Liam Keane (65).
Pearse Celtic B: Eddie Kelly, Craig Roche, Danny Moore, Eoin Harrington, Darren Roche, Sean O’Connor, Gary O’Mahony, Barry Murphy, Keith McCarthy, Stephen O’Leary, Stuart Morrissey.
Subs: Dave O’Connell for Sean O’Connor (55), Alan Harte for Craig Roche (68), Jamie Daly for Stuart Morrissey (103).
Referee: Declan Fogarty (Assistants: Liam Murphy and Grahame Duffy).