Craig Bellamy's side sit second in the section thanks to their goalless draw with Turkey on the penultimate matchday, but their visitors cut the gap down to just two points by defeating Montenegro 2-0.
Match preview
Forget the luck of the Irish, the luck of the Welsh was in during Saturday's fixture with Turkey in Kayseri, where Benfica hotshot Kerem Akturkoglu had the chance to win it for the Crescent-Stars from the penalty spot with 89 minutes on the clock.
However, the Turkish winger's high-pressure penalty struck the post to spark jubilant scenes in Cardiff and beyond; had Akturkoglu's penalty found the back of the net, Turkey would already be making preparations for life in League A for the 2026-27 edition.
As it is, second-placed Wales can leapfrog the Crescent-Stars into top spot should they beat Iceland and Vincenzo Montella's side suffer a shock loss to already-relegated Montenegro, but they could also drop down to the relegation playoff place if they fall to defeat on Tuesday.
The Dragons' current standing would suffice for a promotion playoff against a third-placed League A team next spring, and Akturkoglu's horror moment from the spot means that Wales are still unbeaten in the ongoing Nations League cycle.
However, the hosts are yet to find solutions to their perpetual offensive problems, as Saturday's draw marked the fifth time in eight matches that they have failed to find the back of the net, and their last 720 minutes of football have produced a paltry four goals at a rate of one every two matches.
While Wales' fate is in their own hands, the same is true of Iceland, who will finish third at the very worst and will have the opportunity to fight for top-tier status in next year's playoffs should they slay the Dragons in Cardiff.
Age Hareide's men could not find the formula for attacking success in the first 70 minutes of their clash with Montenegro, but two late strikes from Orri Oskarsson and Isak Bergmann Johannesson were enough to get Tuesday's visitors over the line in Niksic.
No matter what transpires on the final matchday, Our Boys - who competed in League A in 2018-19 and 2020-21 - will end the 2024-25 edition having achieved something that they never managed before; victory in a UEFA Nations League match.
Indeed, the Nordic nation failed to win a single game in either of the first three editions of the tournament, drawing all four matches in the 2022-23 competition and managing to retain their League B status thanks to Russia's expulsion.
The stalemate specialists also fought back from two goals down to hold Wales to an exceptional 2-2 draw in their first Nations League encounter of the campaign in October, although that stretched their winless sequence against the Dragons to five matches since a 1984 World Cup qualifying success.
Wales Nations League form:
D
W
D
W
D
Wales form (all competitions):
L
D
W
D
W
D
Iceland Nations League form:
W
L
D
L
W
Iceland form (all competitions):
L
W
L
D
L
W
Team News
In addition to losing Owen Beck, Wes Burns, Kieffer Moore and Nathan Broadhead before November's fixtures got underway, Wales boss Bellamy was forced to bring Oxford United striker Mark Harris off at half time in the draw with Turkey after a sickening head clash with Joe Rodon.
Rodon remarkably managed to see out the match, but Chris Mepham and Ben Cabango should be on standby, while Harris could now drop out for Daniel James or Liam Cullen if Bellamy decides to err on the side of caution.
Rodon's Leeds United teammate Karl Darlow should keep Danny Ward at bay in between the posts, though, while Ben Davies is now nine caps shy of reaching the 100 mark in a Wales jersey.
As for the visitors, left-back Logi Tomasson must sit this one out due to an accumulation of yellow cards, while captain Aron Gunnarsson was an enforced withdrawal in the first half of the win over Montenegro due to an apparent thigh problem.
The 35-year-old - a long-serving Cardiff veteran from 2011 to 2019 - may therefore be cruelly denied the chance to turn out at his former home this week, where Victor Palsson should operate in defence instead.
Johannesson's strike off the bench on Saturday has given Hareide a dilemma to solve in the engine room, as the 21-year-old could now threaten the place of Stefan Teitur Thordarson, but Andri Gudjohnsen - son of former Chelsea and Barcelona marksman Eidur Gudjohnsen - should continue up top.
Wales possible starting lineup:
Darlow; Roberts, Mepham, Davies, Williams; James, Sheehan; James, Wilson, Thomas; Johnson
Iceland possible starting lineup:
Valdimarsson; Lunddal, Palsson, Ingason, Sampsted; Gudmundsson, Traustason, Johannesson, Thorsteinsson; Gudjohnsen, Oskarsson
We say: Wales 1-0 Iceland
Wales have not been pulling up trees on the attacking front over the past six months, but Bellamy's men should back themselves to keep Iceland at arm's length in Cardiff after their dogged defensive display in Turkey.