Dundalk won but they couldn't rain on Shelbourne’s parade as the home side put in a thrilling second-half performance as Premier Division football returned to Tolka Park after six years.
The Champions were given the mother of all scares by newly-promoted Shels, who were themselves looking to make it two from two in front of 3,010 fans following an opening day win in Cork.
Goals from Andy Boyle and Patrick Hoban had given the Lilywhites a 2-0 half-time lead that the balance of play hardly merited as Shels discovered first-hand the step up in class at Premier level.
Gary Deegan netted in spectacular fashion on first competitive Tolka appearance since returning from a decade away in the UK but couldn’t quiet eke out a second in a dominant second half.
The Lilywhites finished the game with six defenders on the field as an uncharacteristically nervous performance saw them frequently the architects of their own misery.
Karl Sheppard and Ciaran Kilduff were both denied late on by the imperious Gary Rogers, while Chris Shields was on hand to deny Jaze Kabia in the dying moments.
The Lilywhites were below their usual standards in the first half but made it work in their favour as they punished Shels twice from set-pieces.
Deegan had already done brilliantly to deny Michael Duffy what looked a certain opener when Boyle found himself unmarked from a corner and flicked home from a yard out.
Shels had competed well, with front two Ciaran Kilduff and Aaron Dobbs denying Dundalk space to play out, but their only clear chance saw Alex O’Hanlon’s cross just evade the outstretched Kilduff.
The Lilywhites showed their clinical quality two minutes before half time as Duffy’s pinpoint delivery found Hoban unmarked in the middle of the box and he powered his header past Jack Brady.
If Dundalk were somewhat fortunate to find themselves two goals to the good at the break, Shels had learned enough to know they can compete at the top level and re-emerged invigorated.
A well-worked free kick routine between Karl Sheppard and O’Hanlon saw Dobbs go close and, from the resulting corner, Deegan smashed a shot into the top corner with the aid of the post.
Rogers looked the calmest man in white on the night, and he had to be to deny both Kilduff and Sheppard from close range following defensive mistakes.
Another slip saw Kabia race through in the box and, but for a superb tackle from Chris Shields, Shelbourne may have taken something from the game, but Dundalk managed to grind it out.
Shelbourne: Jack Brady; Aidan Friel, Daniel O’Reilly, Luke Byrne, Alex O’Hanlon; Jaze Kabia, Gary Deegan (Ryan Brennan 74), Georgie Poynton (Sean Quinn 71), Karl Sheppard; Aaron Dobbs (Shane Farrell 57), Ciaran Kilduff.
Dundalk: Gary Rogers; Sean Gannon, Sean Hoare, Andy Boyle, Dane Massey; Chris Shields, Jordan Flores (Darragh Leahy 89), Greg Sloggett; Cammy Smith (Daniel Kelly 57), Michael Duffy (Brian Gartland 85), Patrick Hoban.
Referee: Damien McGraith.