Joel Campbell said he always knew Costa Rica were going to beat Uruguay, despite trailing at half-time in their FIFA World Cup opener.
Costa Rica overturned a one-goal deficit to shock Uruguay 3-1 at the Estadio Governador Placido Aderaldo Castelo in Fortaleza on Saturday.
Edinson Cavani converted a 24th-minute penalty to give Uruguay the lead but second-half goals from Campbell, Oscar Duarte and Marco Urena helped Jorge Luis Pinto's men to a surprise win.
Uruguay had been tipped to make light work of their Group D opponents but Arsenal striker Campbell insisted his team-mates never lost faith.
"It wasn't a surprise for us," Campbell told FIFA.com. "We came here to win. We wanted the points and we went for them.
"Despite the fact that they were winning 1-0 we stayed positive. We knew that we were going to win.
"We never thought about losing and thank god we got the result."
Costa Rica will need a repeat performance if they are to get a result against European powerhouses Italy in Recife on Friday and England four days later.
"We've still got two big games to come against two big sides and we hope to put in big performances against them," the 21-year-old added.