Costa Rica's 1-0 win over the Italians yesterday left them needing at least a point against Uruguay in their final Group D game to avoid a repeat of their first round exit at the South Africa World Cup in 2010.
Italy started with a solid 2-1 defeat of England, but Prandelli is now worried.
He rejected claims that the heat and humidity in Recife had played a factor in the defeat. "It was no excuse," said the 56-year-old.
"Costa Rica were well organised, quick and good at winning the ball. After we conceded the goal, we just couldn't get back into it."
Prandelli added: "I'm sure we are going to step up a notch (for Uruguay). We have to, otherwise we are out."
Striker Mario Balotelli missed two first half chances set up by midfielder Andrea Pirlo, who was marked closely throughout as Costa Rica shut out through balls to the forwards.
