Group E has emerged as one of the most open World Cup groups this year despite two teams being pegged as certainties to qualify.
Germany's opening defeat to Japan gave the 2014 winners an immediate hill to climb, while fellow European giants Spain came into the tournament eager for goals, smashing Costa Rica 7-0.
The second matchday threw up another shock, with Costa Rica beating Japan to keep their slim hopes alive.
Here's what each side needs to qualify.
Spain at the World Cup so far
Spain opened up their 2022 World Cup campaign by smashing Costa Rica 7-0 on Wednesday.
La Roja didn't play with a classic striker up front but wasted little time in attack as Dani Olmo, Marco Asensio and Ferran Torres all netted to have them 3-0 up just after the half hour mark.
A second for Torres coupled with further strikes for Gavi, Carlos Soler and Alvaro Morata made it a huge win for Spain, boosting their goal difference with a clinical performance.
The second game against Germany proved to be a much tighter if still incredibly entertaining affair.
Substitute Morata put Luis Enrique's side ahead in the 62nd minute, but fellow replacement Niclas Fullkrug made his mark to draw Germany level and send each side away with a point apiece.
What do Spain need?
Four points from their first two games has Spain in pole position in Group E.
A draw with Japan will see them qualify - La Roja will win the group with a victory or a draw if Costa Rica fail to win. However, there is still a fair amount of jeopardy for Spain heading into their final game.
If Spain lose and Costa Rica and Germany draw, Spain will finish second unless they lose by 13 goals. Hey, stranger things have happened, right?
If Spain lose and Costa Rica win, Spain will be out. If Germany win alongside a La Roja loss, second place between the two will be determined by group goal difference and goals scored. Germany would need to overturn a deficit of eight goals - if the records remain identical, second will be decided on fair play points, which Spain currently lead.
Germany at the World Cup so far
Germany still harbour scars from their embarrassing 2018 title defence and matters weren't helped by a shock defeat to Japan.
Ilkay Gundogan's header had given Hansi Flick's side the initiative, but a second-half capitulation saw them slip to a 2-1 defeat.
They were much better against Spain but couldn't make the most of their superior chances and ended up going behind to Morata's effort. Fullkrug then made it 1-1 with a sweet strike in the 83rd minute.
What do Germany need?
Germany's opening defeat has made their task of reaching the last 16 much tougher as they sit bottom in Group E. However, there is still a chance for the 2014 winners to reach the knockout stages.
If Germany and Spain both win, Germany will finish second. If Germany win and Spain lose, second place will be decided on goal difference and goals scored as explained above.
Here's where it all gets a bit technical.
If Japan vs Spain ends in a 0-0 draw, Germany will qualify with any victory. If Japan vs Spain is a scoring draw, second place will be decided on group goals scored. In the same scenario, if Germany win by two or more goals they will finish second on goal difference with Japan third.
Japan at the World Cup so far
Japan knew they were outsiders for a qualification spot when they were drawn with Spain and Germany, but their opening win against the Germans has put the Asian side in a strong position.
Gundogan's penalty had put Hajime Moriyasu's side behind, but two goals in eight minutes from Ritsu Doan and Takuma Asano gave Japan a historic World Cup win.
However, the group was blown wide open as Japan failed to capitalise on their opening win and were downed by the resolute Costa Rica as Keysher Fuller scored the only goal of the game.
What do Japan need?
With a win and a loss in their first two games, Japan sit second in Group E. They are guaranteed to go through if they beat Spain and will do so as group winners if Costa Rica fail to win.
If Japan and Costa Rica both win, first is decided on goal difference and goals scored - thanks to Costa Rica's heavy defeat to Spain, Japan are comfortably ahead in that tiebreaker.
If Japan can only draw with Spain, they will need Costa Rica to hold Germany to be certain of qualification. Should Japan draw and Costa Rica win, Costa Rica and Spain would go through.
If Japan are held and Germany win by one goal, the group goals scored tiebreaker comes into place. If that is identical, Japan will finish second on head-to-head.
Japan will be out if they lose to Spain.
Costa Rica at the World Cup so far
Costa Rica looked like the whipping boys when they were humiliated by Spain 7-0 in their opener. A number of experienced players looked shellshocked and expectations weren't high for the clash with Japan.
However, they were excellent in defence and Keysher Fuller's late strike proved to be the only goal of the game, lifting the Central Americans off bottom spot and into third. They even have a shot at winning the group.
What do Costa Rica need?
The good news for Costa Rica is that if they win they are definitely through to the last 16. They'll go through as group winners if they win and Japan vs Spain ends in a draw.
If they are held to a draw by Germany, they will need Japan to lose to Spain to be certain of qualification. Spain would have to lose by 13 goals for goal difference to be the same between Spain and Costa Rica for second place.
They cannot qualify if they lose or if both games end in draws.
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