Germany advanced after three straight group wins, while Greece's 1-0 victory over Russia—it's first win at a European Championship since lifting the trophy in 2004 -- saw it scrape through.
However, Katsouranis says Greece will fight “tooth and nail” to win Friday's match in Gdansk, Poland. He will wear the captain's armband in place of suspended Giorgos Karagounis.
Teammates meanwhile said they were irritated by criticism of their crisis-hit country.
Greece has lost five and drawn three of its matches against Germany and former West Germany.