Nobody gave them a chance -- nobody.
Perhaps nobody was listening. Perhaps they didn't want to.
For all of the joking and laughing that Costa Rica would simply turn up in Brazil to make up the numbers, there were those who knew the reality would be different.
"Think big" is the motto that Costa Rica coach Jorge Luis Pinto has always subscribed to.
And the Colombian practices what he preaches -- qualification from the group stage was always going to be achieved if you speak to those within the Costa Rican camp.
Bravado? A fool's hope? No, this is a side which plays with a belief that comes straight from the very top and trickles through the veins of its players.
But it would be foolish to claim that this team has only succeeded because of the spirit which Pinto has engendered -- it has talent too, lots of it.
Greece, also playing in the last 16 of the World Cup for the first time, fell the way of Uruguay and Italy on Sunday, beaten by a side playing with a confidence and belief that appears to be unshakable.
With the game having reached penalty kicks following a 1-1 draw inside 120 minutes, both sets of players had already given everything they had.
Costa Rica's players, who had already suffered the ignominy of having victory snatched away from them, appeared to be running through treacle as they dragged their tired limbs down the field, stretching every muscle and sinew.
But having survived to make it through to penalties, those same players found the strength and skill to write yet another chapter in this incredible tale.
All seven players had scored and, with his side level at 4-4 in the shootout, Theofanis Gekas strode towards the penalty spot.
But there was a look in his eyes -- fear. Time appeared to stand still. The 34-year-old looked at the ball, looked at the goal -- but that look of trepidation never left his face.
Perhaps Navas had noticed, perhaps he hadn't. It mattered little. For when Gekas stepped forward and placed the ball to the goalkeeper's right, Navas flew across to palm the ball away.
Forward came Michael Umana -- a 31-year-old defender who plays in his home country with Deportivo Saprissa.
He placed the ball down, a piece of grass stuck to his cheek courtesy of the sweat which dripped from his brow.
He drew a breath. There was no shimmy, no stutter, no hesitation. As the ball hit the back of the net, those in white shirts forgot the aches and pains which had left their limbs in agony.
Whereas moments ago they could barely walk, now those men draped in the flag of Costa Rica danced their way into the Brazilian night.
"Last night, I dreamed this," Umana told reporters.
"It seems untrue. I was relaxed because I dreamed it. I dreamed it but I didn't tell anyone. I felt very confident.
"This is for my family. It's for the colleagues who got injured before coming here. They're not with us, but they gave us a hand on the pitch."
In the end this proved to be a rather exciting contest -- a world away from what was served up in the opening 45 minutes.
It was Greece that produced the only real opportunity eight minutes before the interval when Dimitris Salpingidis forced Navas into a fine reflex save from close range.
At least the second half was better -- both sides dispensing with their cautious approaches and attempting to take the advantage.
Giorgios Samaras tested Navas with a powerful header as Greece, which qualified following a dramatic late victory over the Ivory Coast, began to move forward with purpose.
But just as it appeared that Greece was ready to take control, Costa Rica pounced.
Captain Bryan Ruiz, the man whose goal saw off Italy, was the hero once again -- taking Cristian Bolanos' pass in his stride before carefully placing his effort beyond the reach of Orestis Karnezis in the Greek goal.
That strike sparked scenes of jubilation on the touchline with Pinto, animated at the best of times, celebrating his team's latest success.
Having only conceded once in three previous games, Costa Rica's defense looked more than comfortable as Greece attempted a fightback.
But with 24 minutes remaining, disaster struck for Los Ticos.
Duarte, one of the team's most dependable members, rushed into a challenge on Jose Cholevas, taking out the Greek player and earning himself a second yellow card.
As referee Ben Williams held the red card aloft, Duarte left the pitch almost inconsolable, leaving behind his 10 teammates to try to hang on.
And hold out it did -- Costa Rica's tenacious approach kept goalkeeper Navas almost unemployed as the clock began to tick down.
But just as its players began to dream of the quarterfinals, Greece, one of the most belligerent teams in international football, proved why it remains so difficult to beat.
With 90 minutes up, substitute Gekas' low shot was only parried by Navas and Papastathopoulous lashed home.
While the Costa Ricans fell to their knees, those in blue continued the onslaught knowing its opponent had been wounded.
It might have even won it inside the 90 minutes had it not been for a wonderful save by Navas, somehow reaching to tip Kostas Mitroglou's header over the crossbar.
With neither side able to find the elusive winning goal, the tie moved into 30 minutes of extra time.
As Costa Rica began to tire, it was Greece which took control and Mitroglou was denied a dramatic late winner by Navas when the striker looked certain to score.
That ensured the tie would be decided on penalties and when Gekas had his effort saved, Umana stood up to rewrite history.
A tie with the Netherlands in Salvador next Saturday is the reward for this Costa Rican team -- a game in which no doubt it will be written off once again.
But for now Costa Rica's players will do what they've done from the very start.
They'll "think big."