Hajime Moriyasu's men head into this one with their fate firmly in the balance but the Asians remain in control of their destiny as a win takes them through, while a point could also suffice depending on the result between Costa Rica and Germany in the other group future.
Luis Enrique's men, meanwhile, are pretty much guaranteed a place in the knockout phase and need just a point from their final group outing to lay any doubts to rest.
Ahead of Thursday's meeting between Japan and Spain, Sports Mole looks at how the squads of the two nations stack up against each other.
JAPAN
Most valuable player:
Daichi Kamada (£26m)
Overall squad value:
£133.4m
Most capped player:
Yuto Nagatomo (135)
Leading goalscorer:
Takumi Minamino (17)
Total caps:
946
Total goals:
88
Oldest player:
Eiji Kawashima (39)
Youngest player:
Takefusa Kubo (21)
Average age:
27.8
SQUAD IN FULL
Goalkeepers: Eiji Kawashima (Strasbourg), Shuichi Gonda (Shimizu S-Pulse), Daniel Schmidt (Sint-Truidense)
Defenders: Yuto Nagatomo (Tokyo FC), Maya Yoshida (Schalke 04), Hiroki Sakai (Urawa Red Diamonds), Shogo Taniguchi (Kawasaki Frontale), Miki Yamane (Kawasaki Frontale), Ko Itakura (Borussia Monchengladbach), Takehiro Tomiyasu (Arsenal), Hiroki Ito (Stuttgart)
Midfielders: Gaku Shibasaki (Leganes), Wataru Endo (Stuttgart), Junya Ito (Reims), Takumi Minamino (Monaco), Hidemasa Morita (Sporting Lisbon), Daichi Kamada (Eintracht Frankfurt), Yuki Soma (Nagoya Grampus), Kaoru Mitoma (Brighton & Hove Albion), Ritsu Doan (Freiburg), Ao Tanaka (Fortuna Dusseldorf), Takefusa Kubo (Real Sociedad)
Forwards: Takuma Asano (Bochum), Daizen Maeda (Celtic), Ayase Ueda (Cercle Brugge), Shuto Machino (Shonan Bellmare)
SPAIN
Most valuable player:
Pedri (£86.6m)
Overall squad value:
£760.0m
Most capped player:
Sergio Busquets (140)
Leading goalscorer:
Alvaro Morata (29)
Total caps:
764
Total goals:
87
Oldest player:
Sergio Busquets (34)
Youngest player:
Gavi (18)
Average age:
25.4
SQUAD IN FULL
Goalkeepers: Unai Simon (Athletic Bilbao), Robert Sanchez (Brighton), David Raya (Brentford)
Defenders: Cesar Azpilicueta (Chelsea), Dani Carvajal (Real Madrid), Eric Garcia (Barcelona), Hugo Guillamon (Valencia), Pau Torres (Villarreal), Aymeric Laporte (Manchester City), Jordi Alba (Barcelona), Jose Gaya (Valencia)
Midfielders: Sergio Busquets (Barcelona), Rodri (Manchester City), Gavi (Barcelona), Carlos Soler (Paris St-Germain), Marcos Llorente (Atletico Madrid), Pedri Gonzalez (Barcelona), Koke (Atletico Madrid)
Forwards: Ferran Torres (Barcelona), Nico Williams (Athletic Bilbao), Yeremi Pino (Villarreal), Alvaro Morata (Atletico Madrid), Marco Asensio (Real Madrid), Pablo Sarabia (Paris St Germain), Dani Olmo (RB Leipzig), Ansu Fati (Barcelona)
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How Japan could line up against Spain
How Spain could line up against Japan