Mark McGroarty came off the bench to score the decisive 68th minute try as UCD overcame defending Ulster Bank League champions Lansdowne on a 21-17 scoreline at Belfield.
Though there was not much to play for given that both sides are well clear of the relegation places, this was nonetheless an intriguing Division 1A contest between two long-standing Dublin 4 rivals.
Numerous players from the clubs have graduated to provincial and international level in recent years, and expectations are certainly high for those who are currently plying their trades at Belfield and Lansdowne Road.
Mounting a strong defence of the eague crown has proven to be difficult in modern times – and like Old Belvedere and St. Mary's College before them – Mike Ruddock's Lansdowne side have had a somewhat mixed campaign to date.
However, seven victories from 14 outings has kept Lansdowne in the upper tier of the top flight, and fifth-placed UCD were just four points behind them with the same number of successes before tonight's clash.
With the two teams aiming to bounce back from disappointing reversals last Saturday, the opening exchanges were played at a ferocious pace, although the visitors were enjoying the majority of possession.
Indeed, Lansdowne took a well-earned lead just six minutes in courtesy of a 25-metre penalty from out-half Tom Kiersey, but UCD were quick to respond with a successful place-kick of their own.
Kiersey's opposite number, Niall Earls, slotted a penalty between the posts with consummate ease, and having bided his time this season while James Thornton was selected in the number 10 jersey, Earls was eager to take advantage of an extended run in the students' starting line-up.
Further indiscipline by Lansdowne presented Earls with a kickable opportunity in the 15th minute and despite being positioned on the right wing, he landed the kick for a 6-3 lead.
After a difficult beginning to the game, UCD were now in the ascendancy and four minutes after they conceded an 18th minute penalty to the dependable Kiersey, Earls contributed his third penalty of the evening from a favourable angle.
However, moving past the half hour mark, the Lansdowne pack were starting to pose a significant threat. Six minutes before the interval, they crossed for the opening try of a lively encounter.
A strong maul on the left wing was finished off in powerful fashion by skipper Willie Earle, who remains one of the league's finest exponents of second row play.
Kiersey was narrowly wide with the conversion attempt but with UCD out-half Earls having to depart the scenes through injury, the momentum appeared to be swinging in Lansdowne's direction.
Rising Leinster star Adam Byrne was also forced off before the first half's conclusion, but in injury-time UCD pounced for a morale-boosting try.
Full-back Andrew Boyle touched down after racing onto a neat kick into opposition territory and with Earls' replacement Liam Bourke comfortably adding the extras, the students brought a 16-11 cushion into the second period.
This was certainly a sucker-punch for Lansdowne, but they regrouped impressively on the restart and thanks to a brace of Kiersey penalties after 44th and 47th minutes, they once again had a slender hold over their opponents.
This forced UCD to increase their intensity and when Lansdowne number 8 Brian Moylett was sin-binned after 58 minutes, it was precisely the kind of lift that the home team required.
Bourke had two excellent chances to restore the UCD advantage during Moylett's absence but much to the relief of Lansdowne, he was well short of the target.
The decisive moment of this Friday Night Lights fixture eventually arrived 12 minutes from the end, and it was Bourke's fellow replacement Mark McGroarty who was on hand to finish off a terrific move in the left corner.
The missed conversion by Bourke did make life hard for UCD in the closing stages but with Lansdowne struggling to create try-scoring opportunities, Bobby Byrne's youngsters held on to secure their eighth league win.
Referee: Andy Brace (IRFU)