Dave Donnelly reports from Greenogue
CIE Ranch came within a couple of minutes of beating UCD to reach a first-ever FAI Cup quarter final, but ultimately the Students' pressure told against the ten men of Ranch.
A Dan Tobin own goal and an Edward Smith header had put the Leinster Senior League side into a shock, but well-deserved, 2-0 lead early on.
Yoyo Mahdy did pull one back for UCD before the break but, despite losing captain Gary Sullivan to a senseless red card 15 minutes from time, the amateurs looked set to hang on for a famous win.
Jason McClelland popped up with a well-taken strike a minute from time, however, and both he and Mahdy doubled their tallies in extra time, while Sean McDonald and Gary O'Neill also scored.
The tie had been moved to Greenogue – the home of Peamount United – as the CIE Works was unsuitable and the club resisted the urge to give home advantage back to the Students.
And the crowd was overwhelmingly behind the reigning Senior Sunday 1B champions, with the colours of the likes of Cherry Orchard and Ballyfermot United dotted among the home fans.
They got something to cheer about almost immediately as Dean O'Brien brilliantly picked Graham Griffiths on the right, and his low cross was turned into his own net by Tobin.
It was unfortunate on the UCD right-back, who had little choice but to attempt an interception, but there was no luck involved in the second seven minutes later.
Right-back Glenn McCabe whipped in a corner and the towering Smith rose unopposed to power a header past the helpless UCD keeper Conor Kearns.
The Students were shell-shocked, but they did gradually gain a foothold in the game and take the sting out of Ranch's attack simply by hanging onto the ball.
And they pulled one back on the half-hour as McClelland crossed low for the lively Mahdy to tap the ball in from close range.
Kevin Coffey could have levelled five minutes before the break with a fine curling effort that seemed bound for the top corner, but Sean Brazil got across well to make the save.
Brazil was in fine form once more after the break as he was at full stretch to deny McClelland's header, which was destined for the bottom corner.
Sullivan saw red for a petulant tackle from behind on Conor Davis, a decision that enraged the home fans but perhaps underlines the difference between amateur and senior football.
Nevertheless, Ranch continued to look comfortable against a UCD side who continued to play the ball through the congestion in the middle of the pitch rather than stretch Ranch.
UCD were always likely to get one more chance before the end, however, and it fell to McClelland, who found a yard of space in the box and lashed a low shot past Brazil.
There was more drama to come inside 90 minutes, however, as Smith looked to have won it with a header Ranch were adamant had crossed the line before being grasped by Kearns.
And a frantic period of play saw Neil Farrugia taken out on the break by McCabe and Gary O'Neill run through on goal before being fouled, but play was called back for the initial foul.
The resulting melée saw the remaining outfield players from both sides clash, and yellow card shown to both Keith Eagers and McCabe, before the final whistle was blown.
Nine minutes into extra time, UCD hit the front for the first time as Farrugia's blocked shot bounces up perfectly for sub McDonald to loop the ball over Brazil from close range.
Mahdy confirmed the win with a low shot after the break before McClelland bagged his second with a fantastic solo effort, and Gary O'Neill added a sixth late on.
CIE Ranch: Sean Brazil; James Bracken, Keith Eagers, Edward Smith, Glenn McCabe; Lee O'Sullivan (Anthony Thomas 98), Gary Sullivan, Dean O'Brien, Graham Griffiths; Liam Cummins (Paul Uzell 66), Patrick Byrne (Jordan Griffiths 79).
Booked: Liam Cummins (40), Glenn McCabe (90+2), Keith Eagers (90+2).
Sent off: Gary Sullivan (74).
UCD: Conor Kearns; Dan Tobin, Josh Collins (Sean McDonald 86), Liam Scales, Evan Osam; Paul Doyle (Daire O'Connor 73) Gary O'Neill, Kevin Coffey (Neil Farrugia 64); Conor Davis, Jason McClelland, Yoyo Mahdy.
Referee: Rob Rogers.
Attendance: 200 (estimate).
Extratime.ie Player of the Match: Edward Smith (CIE Ranch).