Spain and Japan hit the ground running in their respective opening matches but their second matches put fans from both ends in a precarious position whereby they have to approach their final Group E with their calculators out, still unsure whether their boys will be staying on in Qatar after Thursday.
Spain are in a much stronger position at the top of one of the toughest groups in the tournament having followed up their opening 7-0 thrashing of Costa Rica with a 1-1 draw with Germany in a battle of former champions.
A draw at Khalifa International Stadium on Thursday would ensure Luis Enrique's team a spot in the last 16, while a win would secure top spot in the group.
Japan started the tournament with a stunning 2-1 comeback victory over the Germans but they threw away their advantage with a timid performance against Costa Rica, who stole a 1-0 win with their only shot on target in the tournament.
A draw could also get the Samurai Blue into the last 16 for the fourth time in the last seven World Cups but Germany could pip them even then if they beat Los Ticos and score enough goals.
Japan coach Hajime Moriyasu knows what he wants his team to do but appeared less certain about whether they would be able to do it.
"We are going for the win, that is all we need to think about," he said after the Costa Rica loss.
"Beating Germany doesn't mean we can beat Spain, both teams have won the World Cup and we have a lot of respect for them, but we did beat Germany."
Japan fans might have been forgiven a little trepidation when Moriyasu promised yet another tactical shake-up against Spain after his conservative game plan backfired so spectacularly against Costa Rica.
Any World Cup group game where one result would suit both teams will always raise the specter of the so-called "Disgrace of Gijon" 40 years ago in Spain.
FIFA introduced simultaneous final group matches specifically to ensure there would be no repeat of the 1982 West Germany-Austria clash, where a 1-0 win for the former ensured the progress of both teams at the expense of Algeria.
Another early exit for four-time champions Germany might suit Spain very well, but Luis Enrique has committed his team to go all out for victory.
"We will not speculate," he said after the Germany draw. "We will use our full strength and go for the win to secure the top in the group standings."
Just how serious he is about that might only become apparent when his team is revealed after reports in Spain that he might rest captain and midfield stalwart Sergio Busquets.