Stephen Kenny's wait for a first win as Republic of Ireland manager went on as they suffered a 1-0 home Nations League loss to Finland.
Only a late header from captain Shane Duffy rescued a point in Bulgaria on Thursday, and there was to be no Irish hero back in Dublin.
Fredrik Jensen made an instant impact from the bench with the only goal of the game in the 63rd minute, while Kenny's men failed to test Lukas Hradecky for much of a tight contest.
Defeat leaves Ireland already five points off the pace and in need of a lift for their crucial Euro 2020 play-off against Slovakia.
Ireland struggled to break Finland down in a frustrating first half and were grateful for a big early stop from Darren Randolph at the other end.
Robert Taylor's superb pass sent Teemu Pukki clear, but the Norwich City striker could not beat Randolph, who saved smartly with his left boot.
Although the hosts initially improved following the restart, the opener then came at the other end, courtesy of Jensen, just 19 seconds after his arrival in place of Joel Pohjanpalo.
Pukki fed Taylor on the left and a measured pass across the face of goal evaded both Randolph and his defenders, and the lunging substitute slammed into the net.
David McGoldrick might have had a similarly swift impact for Ireland but dallied in front of goal, before Hradecky blocked brilliantly from Callum Robinson.
Finland came on strong again as Taylor worked Randolph at his near post and, after Pukki dragged just wide, the Ireland goalkeeper made an outstanding fingertip save from Nikolai Alho.
Those stops meant Duffy could have again earned a draw as he rose to meet a Robbie Brady corner, but his header looped over as Finland held on.
What does it mean? Ireland lacking spark
Having required a late set-piece goal against Bulgaria, it was all change in the Ireland midfield. But chances were still scarce back in Dublin, with Adam Idah - a debutant earlier in the week - again starved of service.
This was just Ireland's second defeat in their past 14 matches, but they must offer more in attack to settle these hard-fought affairs in their favour.
Taylor pulls the strings
Jensen might have got the goal, but he would not have been in a position to score without the inspired involvement of Taylor. The midfielder's finely weighted passes teed up Pukki in the first half and then the substitute after the break just as Ireland were taking control.
Ireland fail to capitalise
Given the lack of creativity in midfield, Ireland needed to make the most of any chances Finland gifted them. Twice Hradecky put a team-mate in trouble playing out from the back, but Aaron Connolly's poor touch drove him wide, while McGoldrick hesitated at the key moment.
Ireland return to action next month with a mammoth Euro 2020 play-off semi-final against Slovakia. Meanwhile, Finland can look ahead to their friendly at Poland.