The win, authored by the 44th -minute goal by Costa Rican captain Bryan Ruiz, not only put Costa Rica into the second round, the first time since 1990, but also knocked out England from the finals and put the Italians in a tricky situation.
Italy and Uruguay, both former world champions, will have to win their final group match against each other on June 24. Costa Rica have shattered many dreams in this World Cup for sure.
Costa Rica made it to the second round after a gap of 24 years
Ruiz's clinical header gave Costa Rica their fifth victory in the World Cup finals (twice in 1990 and 2014 and once in 2002) and their successive victories over opponents ranked in the top 10.
Costa Rica were dogged in defence and put pressure on every single Italian attacker.
Italy lacked the cutting edge and created very few chances of note. Mario Balotelli, the hero of Italy's previous match against England, failed to convert two easy chances earlier in the game.
The second half saw Italy making attacking changes. They held most of the possession as Costa Rica but could not find the equaliser.