Coach Jorge Vilda warned his Spain team they will be fully tested for the first time at this Women's World Cup in their group-deciding clash with Japan on Monday.
Both sides go into their final Group C game in Wellington having already reached the last 16 and neither conceded in comfortable wins over Zambia and Costa Rica.
But Vilda said that former world champions Japan will be a different proposition as they battle for top spot in the group -- and with it a theoretically easier path in the knockouts.
"I'm expecting a game not like the previous two games," Vilda said on Sunday.
"Japan's a very good team, interprets the game well and has quality players. Tactically they are very well trained and it's a team that can exert pressure on us.
"I think that the difference could be the team that is better in the last third of the field."
Both beat Zambia 5-0 but Spain's 3-0 defeat of Costa Rica, compared to Japan's 2-0 win over the same opponents, means Spain top the group with a superior goal difference of one.
Vilda's side will therefore finish top if the match with Japan ends in a draw.
Their last-16 opponents will both come from Group A, which will be decided on Sunday when co-hosts New Zealand, Switzerland, Norway and the Philippines play their final first-stage matches.
Defending champions the United States or Sweden could then await in the quarter-finals.
But Vilda said he won't take any notice of his team's potential pathway through the knockout phase.
"We have not wasted a second thinking about who we're going to play in the last 16," he said.
"We have no control over that and we're not going to worry about it.
"We want it to be a match that will make us grow as a team and I'm convinced that tomorrow's game is like that, but it's not a decisive match."
There is a fitness doubt over captain Ivana Andres, with Vilda saying the Real Madrid skipper and central defender has "a few problems", without detailing the nature of any injury.
