Greece have played out two goalless draws against fellow World Cup nations Portugal and Nigeria in their build-up to the competition.
However, Santos feels his squad are improving all the time and was pleased with their performance in Wednesday's stalemate in Pennsylvania.
Greece open their World Cup campaign against Colombia in Group C on June 14 and Santos is confident that they have prepared well for the clash in Belo Horizonte.
"I believe that in the first half we were better than Nigeria, we had more control of the game and had more opportunities to score," he said.
"We also saw a very open game, with many chances for both sides. Nigeria had some dangerous opportunities but then we saw Greece manage to make several strong opportunities too. Overall it was a very good test for both teams.
"I believe that these two 0-0 draws have different meanings because I think today we played better than the last game (against Portugal).
"This is part of the progression that we want to see from all the players ahead of the first game against Colombia. Overall I'm satisfied by the effort the players have put in today."
