The Greeks were comfortably beaten in their opening fixture on Saturday as Colombia earned a convincing 3-0 win.
Despite that result, Samaras is confident that Greece can pick up some vital points when they return to action against Japan next week.
"All we can do between now and then is keep positive, keep going and continue to play the same kind of football," he told FIFA.com.
"We created chances against Colombia and that's something we can't forget. On another day, it could have been us winning, and that's something we need to take into this massive match."
Greece take on Japan in Natal on Thursday.