The game represented an opportunity for the best talent still plying their trade in Ireland to make an impression for U19 manager Paul Doolin. And Finn Harps winger Cathal McDaid took the chance by cutting in from the left flank to fire a low shot inside the near post of Welsh goalkeeper John Dowd.
Ireland pressed for a second goal and Jason Lyons headed just over from an Alan Browne cross on the half hour.
The visitors posed more of a threat in the second-half and equalised 20 minutes from full-time when substitute James Stead was allowed time and space eight yards out to smash a shot beyond Niall Corbett.
Disaster struck for Ireland in the 90th minute when Jordan Beck set up fellow substitute Alex Samuel to nod in the winner.
IRELAND: N Corbett (UCD); A Browne (Ringmahon Rangers), P Sweeney (Bray Wanderers), D Corcoran (Carrigaline United), J McGlynn (St Patrick’s Athletic); R Slater (UCD), G Brady (Dundalk), C Harkin (Derry City); M Duffy (Derry City), J Lyons (Salthill Devon), C McDaid (Finn Harps).
Subs: C Byrne (Mervue United) for Harkin (57), A McAlvery (Rockmount) for Lyons, C Shaughnessy (Mervue United) for Corcoran (both 61), C O’Malley (Mervue United) for Corbett (69), P Gannon (Bohemians) for McGlynn, R Curran (Finn Harps) for Browne (both 75), C O’Driscoll (Avondale United) for McDaid (77).
WALES: Dowd; Gruffydd, Gibbons, Tinsley, Cockins; Curtis, Green, Kemp, Hutson; Davies Jamie McDaid.
Subs: Hughes, Joseph, Davies, Beck, Stead, Samuel, Morgan.
Referee: Graham Kelly (Cork).