The Manchester United man lamented Japan's inability to take anything from their opening game after they surrendered a goal advantage before losing 2-1 and says there is no room for caution in their remaining fixtures.
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"We were never really in control of the game against Cote d'Ivoire," he told AFP.
"Greece will attack us because they lost too. We have no option but to attack."
Goalkeeper Eiji Kawashima added that he is confident that the Samurai Blue have spirit to respond to their disappointing start in Brazil.
"We just have to give 100 per cent to win the game," he said.
"We have a good group and we have confidence as well so we can't lose our next game. We believe in ourselves."
Japan have made it out of the group stage in two of their last four World Cup appearances - reaching the last 16 in both 2002 and 2010.