Declan O'Brien's first-half strike proved enough for Drogheda United as they cut Sligo's lead at the top of the Airtricity League to a single point with a hard-earned victory at Hunky Dorys Park.
O'Brien struck with a fine individual effort in the 21st minute, but the Boynesiders were indebted to their keeper Gabriel Sava who denied UCD on a number of occasions.
Two saves in particular were outstanding, one from Paul Corry and the other to deny Robbie Benson, and Drogs boss Mick Cooke had used all his substitutes by the 68th minute as he desperately tried to stem the tide.
Meanwhile, at Dalymount Park an Evan McMillan double ensured a 2-1 win for Bohemians over Dundalk.
McMillan flicked home from an Owen Heary header in the 35th minute and the centre-half powered home his second in first-half injury time following Karl Moore's corner.
Michael Rafter's 70th-minute free-kick gave Dundalk a timely lifeline but despite some late concerted pressure, the visitors failed to draw level by the death.
The meeting of Cork City and Shelbourne produced a fine clash that had everything in it with the exception of goals at Turner's Cross.
There was even a late red card for an innocuous looking challenge by debutant Keigan Parker in what was a very clean game.
Despite a host of chances, neither team could break the deadlock.
Ian Turner and Shane Duggan should have scored for the hosts, and Philip Gorman and Conan Byrne came closest for Shels.