Shelbourne survived an onslaught in Inchicore to somehow bring St. Patrick's back to Tolka Park.
Liam Buckley's league champions utterly dominated for virtually the whole 90 minutes at Richmond Park.
But poor finishing, and a couple of fine saves from man-of-the-match Greg Murray, meant they couldn't put the First Division promotion-chasers away.
In an open game from the kick-off, Shelbourne were unconvincing defensively, gifting Conor McCormack a free header from Ian Bermingham's cross which he planted wide inside the first minute. John
McDonnell's side were not so fortunate two minutes later when St. Patrick's took the lead.
Again it came down the left as Keith Fahey and Bermingham worked the ball to Chris Forrester.
Defender Adam O'Connor appeared to slip as the low cross came in, allowing Christy Fagan all the time in the world to pick his spot.
But St. Patrick's were the ones then left asking questions at the back as Shelbourne punished poor defending to equalise on 10 minutes.
Jordan Keegan picked out Alan O'Sullivan down the inside left channel. The big striker was then allowed turn a little too easily and appear to catch Pat's keeper Brendan Clarke by surprise with a low shot that beat him at his near post.
Utterly dominant thereafter, Brennan, Forrester (twice), Fagan, Conan Byrne and Fahey peppered the Shels goal with Forrester also forcing the save of the half from Murray.
Service soon resumed after the break with Byrne shooting wide before Willo McDonagh did well to nick the ball away as Fagan lurked behind him; Brennan, Fahey and Byrne having carved Shels to shreds down the right.
Shelbourne were hanging on with Philip Hand well positioned at a post to clear off the line from Fahey following a scramble from yet another St. Patrick's corner.
Substitutes Gareth Coughlan and Luke Gallagher provided some respite for Shelbourne on 72 minutes, the latter blazing over when put through.
Back down the pitch, Murray soon had work to do again, pushing Byrne's low drive away at full stretch.
© Irish Times