Costa Rica boss Jorge Luis Pinto says he told his players to "change history" before watching them beat Italy 1-0 to reach the last 16 of the World Cup for the first time since 1990.
Pinto's side were up against three former World Cup-winning countries in Group D in Italy, England and Uruguay.
"We knew that we could make history for Costa Rica and against Italy we have done that," said 61-year-old Pinto.
"It was a beautiful match and the people of Costa Rica deserve this day."
A goal by Fulham striker Bryan Ruiz gave Costa Rica their second victory of the tournament, following a 3-1 win over Uruguay in the opening round of games.
The victory also ended England's hopes of progressing.
"Maybe there are a lot of people who didn't have faith in us because we were in the 'Group of Death'," said Ruiz.
"But the dead are the other ones and we're going to the next round."
Costa Rica will play England on Tuesday knowing a point will be enough to secure top spot in Group D.
"We want to win the next match now and I must ask my players to keep calm and play just as well," added Pinto.
A draw between Italy and Uruguay will be enough to send the Italians through, but they will be knocked out of the tournament if they lose.
"I don't think we need to be negative, we need to think about recovering our energies," said Italy manager Cesare Prandelli.
"We play against Uruguay and whether we qualify depends on that."
Prandelli refused to blame the heat or tactics for his side's loss, but said two missed chances by striker Mario Balotelli proved costly.
"We didn't get our tactics wrong against Costa Rica," said Prandelli. "They were very, very aggressive and we were trying to find different ways into the game but we didn't manage it.
"Mario had two opportunities and if we had scored the game would have been different."