This was a game that had everything - a cup tie involving a missed penalty in regulation time, a 94th minute leveller to force Extra Time (from the Halfway line naturally), and then after 30 goalless minutes a penalty shootout in which neither keeper was tested, with misses deciding the outcome rather than saves.
When the dust finally settled, the Swans progressed 4-3 in the shootout where they will face Wessex League Premier side Baffins New Milton, a trip down to Portsmouth on September 5th. Travel details will be announced in due course.
A scruffy first half saw the hosts thinking they had taken the lead in the first minute, but James Meadows' header was rightly ruled out for offside.
A subsequent header three minutes later from Nathan Smith which came back into play off the Slimbridge post underlined the home sides determination to take the initiative, and with an effort from Stephen Brooks and then a Ronnie Newbery save from George Shrieves, the home side controlled the first 15 minutes, but were unable to take advantage of their dominance.
Slimbridge regrouped and started to create chances at the other end - Casey Collins had an effort blocked after good work from James Tainton, and following a foul on Collins, Charlie Mathews was too high with his free kick.
A nasty clash of heads saw Hadyn Evans forced off with a bleeding scalp on 26 minutes, with Josh Blythe taking his place.
Slimbridge then had a period of pressure as the game moved towards the break - Theo Browne had a good run and shot blocked for a corner, and then a couple of minutes later, sent a dangerous cross into the Irish box that couldn't connect with anyone.
As the game moved toward half time, Browne was felled in the Irish box, but goalkeeper Thomas Ladyman guessed right and pushed Leighton Green's penalty away for a corner, leaving the sides level at the break.
The second half saw the Swans control the game a little more than in the first, with Jack Holmes off target, and Casey Collin's cross finding no-one as it scorched across the goal, as the visitors settled again.
On the hour mark, Meadows played in Shrieves, who was too high with a good chance for the hosts.
Five minutes later, the visitors were ahead - a break down the right flank saw Casey Collins through one on one with Ladyman, and he duly dispatched the chance to put the Swans ahead.
As the minutes ticked down towards ninety, a scramble in the box saw a Theo Browne clearance save the day, and it looked like the Swans were going to hold on.
But in the 94th minute, Ben Farrell came up with a peach of a strike (his second in this sequence of games) from the halfway line - spotting Newbery off his line, he launched the ball forward and it beat the back-pedalling Swans keeper to level things up and send the game into extra time.
Extra time saw very little real action - Josh Blythe's superb goaline stop just before the end of the first period was the only decent chance for either side and so the game went to penalties.
Theo Browne and Olly Sully both went high, missing their penalties, but Irish also blasting two over Newbery's bar, leaving the score 3-3 at the end of the five, with Owen Giles, Casey Collins and Charlie Mathews all converting, so we moved into sudden death.
Jacob Rodgers converted his spot kick, while Nathan Amaning blasted his shot against the bar, sparking delirious scenes amongst the small but mighty Slimbridge contingent.
A long journey, extra time, penalties, getting home in the ridiculously early hours of tomorrow morning - the magic of the FA Cup.
Team: Newbery, Holmes, Rodgers, Lynden, Giles, Mathews, Collins, Evans (Blythe 26), Green (Sully 60), Tainton, Browne
Goal: Casey Collins 65
Supporters Club Man of the Match: Theo Browne
Photo Credit: Rosemai Quarry