In a tournament of shocks and underdogs upsetting some of the established big boys, Belgium's 3-0 victory over Panama on matchday one stood out as a more notable result than it otherwise might have.
Another victory in this match would leave them on the verge of the last 16 with a game to spare, although they will need to wait until at least Sunday - when England take on Panama - to discover whether it will go down to their last match.
Wins for both Belgium and England would confirm both teams' places in the knockout rounds and set up a showdown for top spot between the two group heavyweights, although with the topsy-turvy nature of the World Cup so far it is difficult to determine whether winning the group would actually be a disadvantage at this stage.
As the third-ranked country in the world, Belgium would fancy their chances against any team in the latter stages of the tournament, but the common consensus is that they will need to improve on their opening showing if they are to live up to their billing.
A frustrating first half left lingering feelings of unfulfillment amongst the Belgian fans despite their eventual three-goal win, and against a Tunisian team renowned for being difficult to beat it is likely going to need a more complete display to pick up another win on Saturday.
Starting slowly is a problem which Belgium have suffered from at recent World Cups too, with each of their last 11 goals at the tournament having come after half time.
However, it is important not to lose sight of the fact that any three-goal victory at the World Cup is a good result, and Belgium are now unbeaten in their last 10 World Cup group games, including victories in each of their last five.
Belgium are also unbeaten in 20 games across all competitions stretching back to September 2016 - the second-longest streak at this World Cup behind only Spain - scoring 67 goals in that time at an average of more than three per game.
Martinez's star players also started to find their rhythm in the second half of the win over Panama, with Romelu Lukaku scoring twice and both Kevin De Bruyne and Eden Hazard helping themselves to assists.
There is a level of expectation surrounding this Belgian team, though - one unbefitting of their modest World Cup history but understandable considering the talent at their disposal - and it may take more than just a narrow win on Saturday to convince some of the more demanding fans, even if it is enough to qualify for the knockout rounds.
Recent form: W
Recent form (all competitions): WWDWWW
Few would argue that Tunisia deserved more from their opening fixture against England, but the nature of their late defeat would have been difficult to take for the African nation.
The Carthage Eagles withstood some heavy pressure in the first half and somehow went into the break all square, benefiting from a dubious penalty after England had missed a host of clear chances.
There was minimal attacking intent from Tunisia after Ferjani Sassi's 35th-minute spot kick, with that proving to be their only shot on target of the match, but they will likely need to throw more caution to the wind with their World Cup campaign now hanging in the balance.
Defeat to Belgium could confirm their World Cup exit with a game still to spare should England also overcome Panama, while even a draw would leave them in deep trouble unless Panama were to pull off an almighty shock on Sunday.
Going out to win games could prove to be a suicidal task against a Belgian team boasting so much creative talent, but Tunisia will need to risk allowing the likes of De Bruyne and Hazard the space to flourish should they find themselves behind going into the final half-hour or so.
Winning games at a World Cup has also proven to be a particularly difficult task for Tunisia; they are now on a 12-game winless run at the competition which stretches all the way back to 1978.
Indeed, the only team to have suffered a longer winless run in World Cup history is South Korea, who went 14 games from 1954 to 1998, so the formbook is very much against Tunisia ahead of what looks like their most difficult group game on paper.
It would take a major upset for the African nation to keep their last-16 hopes alive, then, but this tournament has not been lacking for those and Tunisia did at least ensure that they had experience of playing against some of the world's best teams in the buildup to the World Cup.
A come-from-behind draw against Portugal and narrow late defeat to Spain threw up results which would not be of great use to Tunisia on Saturday, but the performances in both matches - in addition to their close miss against England - would have offered some encouragement to Nabil Maaloul's side.
Recent form: L
Recent form (all competitions): WWDDLL
Belgium have no new injury concerns for this match and so could name an unchanged side from the win over Panama.
Lukaku will lead the line again following his brace in the opening fixture, and one more goal would see him level with Jan Ceulemans as the highest-scoring Belgian at major tournaments with six.
Hazard is also a man in form having directly contributed to 16 goals in his last 15 games for his country, scoring eight times and assisting eight more.
Tunisia will be forced into at least one change after goalkeeper Mouez Hassan damaged his shoulder early on against England, bringing a premature end to his tournament.
Farouk Ben Mustapha is expected to replace him in the starting lineup, although Maaloul is likely to keep changes to a minimum elsewhere.
Belgium possible starting lineup:
Courtois; Alderweireld, Boyata, Vertonghen; Meunier, De Bruyne, Witsel, Carrasco; Mertens, Lukaku, E Hazard
Tunisia possible starting lineup:
Ben Mustapha; Bronn, S Ben Youssef, Meriah, Maaloul; F Ben Youssef, Sassi, Skhiri, Badri, Sliti; Khazri
Head To Head
This will be the fourth meeting between the two sides, and as things stand the head-to-head record is evenly matched at one win apiece and one draw.
These two sides have met before at a World Cup too, with their 2002 Group H clash ending all square at 1-1.
We say: Belgium 2-1 Tunisia
Tunisia should put up a sterner fight than Panama, but Belgium still have the quality to overcome them. At one point or another Tunisia will need to throw caution to the wind, and that could suit the Red Devils.