David McMillan 's first half header gave UCD the three points as St Patrick's Athletic surrendered top-spot in the Airtricity Premier Division at the Belfield Bowl on Monday night.
McMillan rose superbly from a right-wing cross by Paul Corry in the 33rd minute and the striker headed the ball into the top corner of the Pat's goal.
The Saints struggled to break down the excellent College defence throughout the game with Shane Gutherie and Paul Byrne wasting headed chance to rescue a point on 69 and 90 minutes respectively.
UCD made two changes from the side that drew with Bohemians last Friday night.
Ciaran Nangle came in for Sean Harding, while Dwanye Wilson replaced Peter McMahon.
Pat's boss Pete Mahon opted for a number of alterations to his team after the home loss to Shamrock Rovers.
Ian Bermingham, Brian Cash, Gareth Coughlan, and Conor Sinnott started for the Saints as Damien Lynch, Stuart Byrne. Paul Byrne and Alex Williams dropped out.
St Pat's went very close to opening the scoring in the seventh minute as UCD struggled to clear a Conor Sinnott corner. Gareth Coughlan's shot was heading for the net but, with a combination of three defenders, College managed to clear.
UCD also looked bright in the opening stages, with Ciaran Kilduff heading over from Nangle's long ball.
Pat's were looking to get lone striker Vinny Faherty involved as much as possible as UCD's defence, the second best in the league going into tonight's game, looked uncharacteristically shaky.
However in the 20th minute Students defender Brian Shorthall slipped the ball through to Chris Mulhall on edge of the Saints box.
The midfielder's shot was well saved by Gary Rogers, who then dived on the ball, but the referee Padraig Sutton waved away protests that the Pat's keeper brought down Kilduff in the process.
Pat's should have gone in front in the 26th minute when Brian Cash's looping cross was spilled by Billy Brennan in the UCD goal.
Coughlan's shot was heading for the net but UCD captain Evan McMillan cleared the ball to safety.
The Students took the lead in the 33rd minute, David McMillan escaped his marker and headed the ball past Rogers.
They almost doubled their lead three minutes later when Pender's sliced clearance went inches wide for a corner.
In the run up to half-time the Saints were struggling to carve out any clear cut chances despite plenty of possession and as referee Sutton blew his whistle for half-time, it was difficult to distinguish which side of the two sides were on top of the table.
Pat's started the second half on the offence with Coughlan's pinpoint cross wastefully headed over by Faherty in the 51st min.
Rogers had to be alert five minutes later as the former Galway goalkeeper parried Kilduff's snap shot from eight yards.
Kilduff was threatening again on the hour mark but his effort from the edge of the box was poor with pressure coming for Saints defender Conor Kenna.
Pat's made a double substitution in the 64th minutes as Ryan Guy and Paul Byrne replaced Conor Sinnott and Coughlan.
The away side, now completely dominating in possession, continued to fling balls into the UCD box.
Shane Gutherie the next to threaten from a Pender cross, but his header sailed over.
Williams made his entrance with 15 minutes left on the clock as Pat's looked to break through the tight UCD backline.
Guy's effort from distance five minutes later didn't trouble Brennan in the Students goal.
UCD were now content to run the clock down but Pat's almost grabbed an equaliser in the 90 minute as Paul Byrne's dipping header found the roof of the net.