Luis Enrique may choose to rest Sergio Busquets as the Spain captain is one booking away from a suspension
Although the 2010 winners only need a point to qualify for the last 16, all four nations in Group E have a chance to go through on Thursday.
Seven outfield players in Spain's 26-man squad are yet to feature in Qatar but Enrique will not give them game time just for the sake of it.
"Some may end up not playing at all - we all know how it works," he said.
"It is a reality, we have spoken about it with the players.
"Don't write Costa Rica off, they can win against Germany. Any of the four nations can still go through and that is very telling.
"We are here to win seven matches. We want to be winners of this group."
Japan came back to upset Germany in their first game but then lost 1-0 to Costa Rica, leaving they and Costa Rica a point behind group leaders Spain as Japan aim to reach the last 16 for the second straight World Cup.
"I would like the players to play well so they can increase their value in the eyes of the Japanese people and I hope we can impart hope when they look at our games and our play," said coach Hajime Moriyasu.
Japan defenders Takehiro Tomiyasu and Hiroki Sakai are both doubtful with hamstring injuries.
Midfielder Wataru Endo could miss out after missing training due to a knee problem.
Spain midfielder Gavi, 18, is doubtful after missing training due to a minor injury.
Captain Sergio Busquets is one booking away from a suspension and is set to be rested.
-- Courtesy of BBC Sport