SUBSTITUTE Fredrik Jensen ruined Stephen Kenny's big night as he came off the bench to fire Finland to Nations League victory over the Republic of Ireland.
Jensen had been on the pitch for just 18 seconds when he fired the Finns ahead somewhat against the run of play to ensure the manager's first home game ended in a 1-0 defeat at an empty Aviva Stadium.
After a pedestrian first half, Ireland finally established some momentum with Aaron Connolly and substitutes David McGoldrick and Callum Robinson threatening either side of Jensen's strike, but as the home side pushed for an equaliser, they were hit repeatedly on the counter.
Skipper Shane Duffy headed agonisingly over at the death after keeper Darren Randolph had kept Finland at bay, but there was no way back.
The defeat, coupled with Thursday night's 1-1 draw in Bulgaria, left the Republic still awaiting a first Nations League win and Kenny with as many questions as answers as he attempts to draw up a blueprint for next month's Euro 2020 play-off in Slovakia.
Having handed a debut to 19-year-old striker Adam Idah in Bulgaria, the manager included his former Under-21s skipper Jayson Molumby in a entirely new midfield trio alongside Harry Arter and Robbie Brady.
Brady was prominent as Ireland attempted to take the game to the visitors from the off, although John Egan had to be alert to prevent Robert Taylor from latching on to Teemu Pukki's knock-down.
The home side were caught once again with nine minutes gone when Taylor slipped Pukki in on goal, only for Randolph to make a fine block as he raced from his line.
Taylor and Rangers midfielder Glen Kamara were causing problems for Kenny's men as they linked with front two Pukki and Joel Pohjanpalo, whose movement was proving an issue for central defenders Egan and Duffy.
Duffy did just enough to prevent Pohjanpalo from making a decent connection with Nikolai Alho's inviting 26th-minute cross, but Ireland gradually worked their way into the game with Idah and Aaron Connolly belatedly starting to see a little of the ball, although with little or no penetration.
Ambitious appeals for a 40th-minute penalty were waved away by Italian referee Fabio Maresca after Duffy had gone to ground under Juhani Ojala's challenge, and the game remained all square at the half-time whistle.
Connolly returned with the bit between his teeth as he started to run at Alho and Duffy glanced a Brady free-kick well wide before Molumby's cross was deflected dangerously across goal with the Republic finally making an impression.
The Brighton striker fired into the side-netting after Brady had dispossessed Kamara, and Callum O'Dowda curled a 57th-minute effort wide of keeper Lukas Hradecky's right post as the impetus remained with the men in green.
However, it was the Finns who took the lead when Jensen made an instant impact, getting involved in a left-wing throw-in before heading to the far post to convert Taylor's inviting cross.
David McGoldrick, on as a 66th-minute replacement for Idah, my have followed suit after fellow newcomer Callum Robinson dispossessed Ojala and played him in, but he delayed and his shot was smothered.
Connolly and Robinson both had shots saved in quick succession with Ireland pressing for an equaliser, but Randolph had to repel attempts by Taylor and Alho to prevent further damage with Pukki also flashing just wide.
However, Duffy almost repeated is heroics in Sofia when he met Brady's 88th-minute corner with a thumping header, but this time cleared the crossbar.