Stephen Kenny's side lost on penalties to Slovakia in their playoff semi-final on Thursday, while Wales faced disappointment of their own as they lost 3-0 to England in a friendly.
Ireland missed a series of golden opportunities to beat Slovakia in normal and extra time, but the playoff finished goalless and penalties were required in Bratislava.
Matt Doherty's spot-kick miss ensured Kenny's men will be staying home next summer after missing out on a place in the rearranged European Championship finals.
Kenny is still searching for his first win since succeeding Mick McCarthy after drawing with Bulgaria and losing to Finland in his first two games, both in the Nations League.
The late 1-1 draw in Sofia can be considered a point gained on the face of it, but Ireland were poor in their 1-0 home reverse to Finland - Fredrik Jensen scoring the only goal.
After the heartbreak in Bratislava, the Boys in Green now switch focus back to the Nations League. They are third in Group B4 with that solitary point from the first six on offer.
Wales lead the way with six points from six, having followed up a late 1-0 win in Finland with an even later 1-0 win at home to Bulgaria.
That made it four wins in a row for Wales without conceding, but that run - and indeed their eight-match unbeaten streak - came to an end at Wembley on Thursday evening.
After a promising start, Ryan Giggs's side conceded three sloppy goals against rivals England, who were fielding something close to their second-string side.
Giggs admitted after the game that lessons will be learned from that match, but the damage goes beyond the scoreline, with target man Moore limping off in the first half.
The pressure is very much on Republic of Ireland to pick up the win in Dublin this weekend, though, which should suit the visitors nicely.
Republic of Ireland Nations League form: DL
Republic of Ireland form (all competitions): LWDDLL
Wales Nations League form: WW
Wales form (all competitions): DWWWWL
Aaron Ramsey missed the England game due to coronavirus protocols, but he has been training with Juventus and is back available for Wales's double-header with Ireland and Bulgaria.
Moore has been a key player for Giggs since breaking onto the international scene last year, but he is a major doubt after injuring his toe in the England defeat, so Tyler Roberts - an attacking midfielder by trade - may have to lead the line.
As for Ireland, Kenny will surely have to make changes on the back of the trip to Slovakia, having seen his side give their all in a two-hour battle.
Republic of Ireland possible starting lineup:
Randolph; Doherty, Duffy, Egan, Stevens; Browne, Hourihane; O'Dowda, Hendrick, Brady; Long
Wales possible starting lineup:
Hennessey; C.Roberts, Mepham, Rodon, Davies; Levitt, Ampadu; Wilson, Brooks, James; T.Roberts
We say: Republic of Ireland 1-2 Wales
Republic of Ireland and Wales have met regularly in recent years, with the Dragons doing the double in the most recent UEFA Nations League campaign.
Kenny's side are out of form and will surely be fatigued on the back of their gruelling match with Slovakia, so we are going with a narrow away victory on Sunday.