Georgios Samaras' last-gasp penalty against Ivory Coast on Tuesday ensured Greece progress from the group stage at a World Cup finals for the first time.
Samaris put Greece in front three minutes before half-time against Ivory Coast after replacing the injured Panagiotis Kone.
The Olympiacos midfielder knows Costa Rica must not be taken lightly after they surprisingly topped Group D, but the 25-year-old is backing Fernando Santos' side to reach the quarter-finals.
He told Sport Day newspaper: 'I've watched all three (Costa Rica) matches in the league.
"It does not have the players names of Colombia or Ivory Coast, but the team is in every sense of the word and it makes (them) even more dangerous. The fact that they finished first in a group involving Uruguay, Italy and England says it all.
"For months we said that we were aiming at qualification for the last 16.
"We knew our potential, we did feel proud and hopeful for the future. I think we can go further. I have a good feeling for the game against Costa Rica."
