RECIFE, Brazil (AP) -- Had Costa Rica been a less resilient team, it might still be stewing over referee Enrique Osses' refusal to award a penalty when explosive striker Joel Campbell was taken down in the area.
Playing confidently and attacking relentlessly, Costa Rica seized control of Group D and clinched a place in the knockout round of the World Cup with a 1-0 victory over four-time champion Italy.
''The first objective we have already achieved, and now let's see,'' Ruiz said of the Costa Rica's assured place in the Round of 16. ''Of course, we want to go forward, as far as possible.''
The triumph might have been more lopsided if not for Italian goalkeeper Gianluigi Buffon, who made several diving saves.
Entering the tournament as the second-place team in CONCACAF qualifying, behind the United States, the Costa Ricans were apparently the weakest team in a group featuring former World Cup champions Italy, Uruguay and England.
Not anymore. They've reached the second round for the first time since 1990 and can top the group with a draw or better against England, which was knocked out of contention because of Friday's result.
''Today is a very special moment for us,'' Costa Rica coach Jorge Luis Pinto said. ''We knew that today we could make history for Costa Rica and we've been able to do so.
''I've told my team we have to keep calm. We're here and we want to stay,'' Pinto added. ''It's not going to be easy. A World Cup is never easy.''
The gravity of the victory for the small Central American nation was evident in the way several players reacted to the final whistle by collapsing to the turf the way tennis players often do after winning Grand Slam titles.
Nearly an hour after the match, when team captain Ruiz accepted the player of the match award, Costa Rican fans could be heard still celebrating just outside the stadium.
Meanwhile, players began to receive photos on their smartphones of celebrating fans in the streets in the Costa Rican capital, San Jose, and beyond.
''Maybe we hadn't realized how important this victory was after the match, but now we do,'' Ruiz said. ''Thank you to the fans who have supported us all along, and those who haven't supported us maybe believe in us right now.''
Costa Rica entered its match against the Azzurri exuding confidence after opening with a surprising 3-1 comeback victory over Uruguay, a semifinalist in 2010.
But Uruguay striker Luis Suarez, who nearly led Liverpool to an English Premier League title this past season, missed that game and there were some questions about how Costa Rica would handle one of the traditional powers at full strength.
By the fulltime whistle, Costa Rica had matched Italy in shots with 10 and shots on goal with six, despite having only 42 percent of possession.
''It's been a great triumph, but on the other hand, all the team was convinced this was possible,'' Ruiz said. ''After we won against Uruguay, we were really motivated.''
A minute before Ruiz's goal, Campbell swooped on a back pass that had been misplayed by Giorgio Chiellini and charged into the area, where he was bundled over by the veteran Italian defender.
There was no penalty forthcoming, but while coach Pinto was screaming and waving his arms in apparent disgust, the Ticos regrouped and mounted their decisive attack.
If such relentless focus didn't prove that Costa Rica was for real, the way the Ticos held firm in the second half did.
Meanwhile, it seems increasingly like CONCACAF qualifying may have been under-rated. After all, Costa Rica had qualifying victories over the U.S., Honduras and Mexico, which also made it to Brazil. The Ticos also held Mexico to a draw in the Azteca.
Italy coach Cesare Prandelli wasn't surprised by the performance of the Costa Ricans.
''They have quality players,'' Prandelli said. ''It was the squad with the lowest profile in the group but you don't advance on profile alone in big tournaments.''