While the Costa Ricans have surprised many by their run in the tournament, Santos is confident that his side will be fully prepared to face them this weekend.
"We have time to think about the match with Costa Rica. We will go back to our base, think about it and study our opponents," he told FIFA.com.
"We have to pay a lot of attention to this game, they came out top in the 'Group of Death'. As a result we cannot allow ourselves to underestimate them."
Greece and Costa Rica meet in Recife on Sunday night.