Junior Diaz was at the heart of every celebration when Costa Rica beat Italy 1-0 in Recife to book their place in the knockout stages. The slight and slender winger, who packs bags of pace and power, was mobbed by his team-mates after whipping in the cross that picked out Bryan Ruiz for the game’s only goal. And he was mobbed again at the final whistle as Los Ticos pulled off the biggest win in their history.

“It’s extra special for me because I was never guaranteed to be in the starting XI,” he told FIFA.com after the celebrations died down down at the Arena Pernambuco. Diaz, who plays with German side Mainz, breached the first team only as a replacement for left-back Bryan Oviedo, who broke his leg earlier this year. “To be a part of creating the goal and helping the team, this is the best moment in my career and one of the best in my life.”

Diaz is a man living an unlikely dream. His enthusiasm is contagious. And his beaming smile transmits the special brand of excitement pervading this Costa Rican team as they chase big dreams here in Brazil.

“We made history,” he added, as his team-mates walked by and slapped him on the back. He basked in the spot-light. “We dared to dream that we could beat Uruguay and we did,” he said of their opening game in Fortaleza six days ago. It was Diaz’s FIFA World Cup™ debut. “Then we dreamed we could beat Italy and reach the second round and we did. Now we can dream even bigger.”

This is the best moment in my career and one of the best in my life.

Junior Diaz, Costa Rica winger

Diaz’s seamless performances so far are indicative of the surprising depth in this Costa Rican team – who are shocking everyone except their passionate traveling fans. “We lost a few players along the way to injuries,” he said, while Italian icons and former world champions Andrea Pirlo and Gigi Buffon, knowing the better team on day had won, sulked through their post-match interviews. “It wasn’t just Oviedo at left-back, but others fell along the way too,” he added, signalling down the hallway to hobbled striker Alvaro Saborio, who has come to be with the team despite serious injury. He rolls around on a scooter he pushes with his good leg; his mates help him if he needs it.

“These are major players for us,” Diaz went on. “These guys were in the qualifiers and they did such a good job. But we have cover. You don’t make this team just because you are Costa Rican. All of the players on this team – 1 to 23 – can play,” he insisted. “When somebody goes out, someone else steps up to take his place. This is what you need to win. And this is what we have.”

Diaz searches for his mobile phone, lost in the celebrations. He has a call to make, to his father. Diaz senior was one of the shining stars of Costa Rican football in the 1980s, but when Los Ticos qualified for their first  World Cup in 1990, he was left out and didn’t make the trip to Italy. There was public outcry over his omission, but then-coach Bora Milutinovic was unmoved. “My father was so sad about it,” added Junior, who was just a kid then. “But now I have the opportunity to be here at a World Cup and make history. It feels like he is here now, that through me, this is his World Cup too. I am happy as a son and he is happy and proud as a father.”

Eager to savour the moment even more, Diaz rushes off to his team-mates with his eyes glowing. This is a man who wants to make the most of this chance and let nothing slip away.