Both sides endured contrasting emotions after their respective first matches of the tournament. Marc Wilmots' side were comfortably second-best as they fell to a morale-sapping 2-0 defeat to Italy in their opening game.
That, understandably, led to plenty of questioning as to whether the Red Devils can live up to their pre-tournament billing, where they were pipped as one of the favourites to lift the title this summer. Instead, they are in serious danger of an embarrassing early exit.
If they are to control their own destiny in the 'Group of Death', then they simply have to beat the Irish, who were only prevented a first win in this tournament since 1988 by Ciaran Clark's headed own goal as they drew 1-1 with Sweden on Monday and will be keen to bounce back.
A respectable draw in many ways, Martin O'Neill and his side came away with an abundance of positives, although they will be disappointed having been the better team for the first 50 minutes - their dominance rewarded by Wes Hoolahan's excellent opening goal just after the interval.
Committed to the cause and hard-working throughout, The Boys in Green did extremely well to keep the Swede's star man Zlatan Ibrahimović quiet. Remaining even throughout, their only failure was to let slip their control of the game after taking the lead,
On the other hand, the Belgians - who remain well capable of reversing their situation - were woefully below-par in their first game against Italy. As such, despite their quality, their chances of success this summer were severely damaged by their result, but more importantly their performance.
So poor it was, Belgium No.1 goalkeeper Thibaut Courtois publicly declared that they were tactically defeated by the Italian's well-organised collective. That was the opposite message of his manager, with the two reportedly clashing over the 'keeper's comments on the plane back to their training camp later that night.
That kind of infighting reflected the disfunction and disorganisation of their performance on the night, something Ireland will hope to take advantage of on Saturday despite being the worst ranked side in the group.
The Republic's attacking approach they showcased for much of the game against Swede is unlikely to change now, given their need to win, although both sides will be caught in a difficult situation where they must carefully balance their attacking and defending approach.
There is little margin for error for the Red Devils, with Italy already guaranteed to finish above them having sealed their place in the Round of 16 with an injury-time winner against Sweden in Toulouse on Friday.
But the Irish will be equally as keen to register a first three points, given that it would put them in an excellent position to reach the knockout rounds against all odds.
That sets up what is sure to be one of the most exciting matches of the tournament to this point, Belgium likely to go all guns blazing in search of a win, but Ireland retaining enough threat of their own to deliver a blow to their chances of reaching the last 16.
Marc Wilmots could make changes from the starting eleven that fell to defeat against Italy with Kevin De Bruyne's place in the eleven in doubt due to a minor hamstring injury.
The Belgium boss stressed in a press conference that it was an injury previously sustained before international duty but indicated that the Manchester City midfielder had been suffering from pain which required extra rest.
Although De Bruyne returned to full training towards the end of the week, he is likely to be subject to late fitness tests to declare the extent of his involvement.
In the aftermath of the Italy game, Wilmots admitted that the midfielder's disappointing performance in Lyon might have been down to being "tired after a busy season" as he admitted that he's "not quite [been] at full pelt" in training.
Eden Hazard also required extra time to recover after the opening match. The Chelsea winger played the full 90 minutes after it had been feared a knock sustained in training a few days earlier would rule him out, but according to Wilmots is at 100 per-cent fitness to face Ireland after recovering from a slight knee knock and groin pain.
Otherwise, Belgium could make changes from those who disappointed in their first game - Romelu Lukaku facing tough competition for the role of lone striker, particularly after his pitiful performance against the Italians.
Wilmots told reporters a few days ago that he did not know whether he would select the Everton striker to once again lead the line, referring to the "number of options" he has - with Divock Origi and Michy Batshuayi possible replacements.
Ireland have confirmed that Jonathan Walters will miss out after aggravating his already-injured Achilles against Sweden.
The Stoke City forward had battled the problem throughout the build up to the tournament and admitted after their first game that the injury troubled him as early as the first minute, admitting that it felt "sore" and it was "the right thing" to come off after 64 minutes.
The 32-year-old missed training on Thursday and O'Neill ruled him out of contention in a press conference on Friday as he insisted that he is "not going to be fit" and that they will "have to make at least one change" and "will have a look at it and decide on it" in the hours before the game.
Otherwise, however, the Republic have few injury worries with West Bromwich Albion winger James McClean, who came on for Walters against Sweden, the favourite to replace him from the outset.
Belgium haven't lost to Ireland for 50 years, including beating them in a play-off to qualify for the 1998 World Cup, also in France.
Since that 3-2 friendly loss in 1996, Belgium have won two and drawn four of the six meetings between the two teams.
Belgium and Ireland haven't met since November 1997, when the former won 2-1 at home in a World Cup qualifier.
In that same qualifying campaign, Belgium coach Marc Wilmots played against Ireland in the return fixture - a 1-1 draw at Lansdowne Road in Dublin.
This is the first fixture between the two at a major tournament, with the Republic never having beaten the Belgians in a competitive meeting.
The Red Devils have lost six of their last eight games at the European Championships, winning the other two but losing 2-0 in their last three successive games.
Belgium's run of conceding a goal in their last eight games is their longest run without a clean sheet since going nine games without a shut-out between May to September of 1986.
Belgium haven't scored in the Europan Championship finals since 2000 against Sweden, their final opponents in this summer's group stages.
This is Ireland's third Euros and they have never reached the knockout rounds in their previous two tournaments in 2012 and 1988.
Ireland's last win at the tournament came in their first ever Euros game in 1988 when they beat England 1-0, drawing two and losing four of their last six matches since then.
The Republic are yet to score more than one goal in a game in this competition.
Including qualifying matches, nine of the Republic of Ireland’s last 11 matches in the Euros have seen two or less goals scored.