Shelbourne, whose only league defeat this season came at the hands of Shamrock Rovers, almost doubled that tally against their Dublin rivals tonight but for a last minute Owen Heary strike.
Rovers, who led through striker Trevor Molloy's first half effort, appeared on course for victory until Heary poked home amid a goalmouth scramble three minutes into injury time.
Waterford United suffered their fourth successive league defeat when Paul Doolin's Drogheda United recorded a 3-1 victory away at the RSC.
The visitors set the wheels in motion as early as the second minute when Barry Molloy thumped home a volley from 25 yards.
Fifteen minutes later Drogheda doubled their advantage when John Lester beat Waterford keeper Dan O'Connor with a fine strike following good work from Andy Myler.
Later in the first half, Myler then turned goalscorer when reacting quickest to Steven Gray's knock on and finishing to the Waterford net.
Kevin O'Brien scored for the home side in the dying minutes of the game but it was too-little-too-late to stop Drogheda marching into second spot in the table.
St Patrick's Athletic's recent run of decent form was halted when Alan Murphy's 23rd minute goal gifted Derry City a win at Richmond Park.