The Dragons are top of League B Group 4 with two rounds of fixtures to play, one point clear of Finland, while the Republic of Ireland are out of contention for promotion.
In the absence of manager Ryan Giggs, who has agreed to step down for the November fixtures due to his recent arrest for an alleged assault, Wales played out a stalemate with the United States on Thursday.
It was a game of very few chances and it is difficult to see exactly what stand-in boss Rob Page will have taken away from the match, besides handing out a few more debuts.
The goalless draw against a youthful USA side makes it just one defeat in 12 for Wales, with their only loss since June 2019 coming in a friendly against England last month.
Scoring goals is becoming a major issue for the Dragons, having now played out two goalless draws in their last three matches and scored just three times in their last six games.
When those goals have arrived, they have been in the final 10 minutes of games, earning late victories over Finland in Helsinki and Bulgaria home and away.
All that matters, though, is that Wales top their group ahead of back-to-back home encounters with Republic of Ireland and Finland.
With Finland favourites to beat Bulgaria in Sofia on Sunday, it may well come down to a final game shootout in Cardiff next week for promotion to League A.
Finishing top is out of the question for the Republic of Ireland, having failed to win any of their four matches so far in this latest edition of the competition.
Indeed, they are without a win in eight matches when taking the 2018-19 tournament into account.
Stephen Kenny's side are one point above bottom side Bulgaria, whom they host in their final fixture next week, with relegation the biggest concern.
The Boys in Green were well beaten by England in a friendly on Thursday, going down 3-0 at Wembley, and are now winless in seven overall since beating New Zealand 12 months ago.
Stopping the rot in time for the next qualifying campaign is going to be a huge challenge for Kenny, but victory in Cardiff on Sunday may well act as a turning point.
Wales Nations League form: WWDW
Wales form (all competitions): WWLDWD
Republic of Ireland Nations League form: LDDLDL
Republic of Ireland form (all competitions): DLLDLL
Kieffer Moore was brought into Wales's starting lineup against USA in one of nine changes and was surprisingly given more than an hour.
The Cardiff City striker is the hosts' only recognised striker and will therefore almost certainly start on Sunday, unless Page decides to put his own spin on things following last month's stalemate between the sides in Dublin.
Having had a batch of coronavirus-related withdrawals last month, the Boys in Green lost Callum Robinson ahead of the Wembley trip after he tested positive for COVID-19.
Alan Browne has also since tested positive, but he is not believed to have been in close contact with any other players or backroom staff members.
Aaron Connolly is the other fitness doubt, with Kenny expected to make changes in Cardiff.
Wales possible starting lineup:
Ward; Williams, Mepham, Rodon, Davies; Ampadu, Smith; Bale, Brooks, James; Moore
Republic of Ireland possible starting lineup:
Randolph; Doherty, O'Shea, Long, Brady; Molumby, Hourihane, Hendrick; Curtis, Idah, McClean
We say: Wales 1-0 Republic of Ireland
This will be the sixth meeting between these sides in the last three years. Wales have lost only one of those past encounters - albeit the biggest game of the lot in World Cup 2018 qualifying.
The Dragons have been incredibly tough to beat over the past 18 months, while Republic of Ireland just cannot seem to pick up a victory, so we are tipping the hosts to edge this one.