The Roma midfielder helped the Italians get off to a winning start against England in Group D but face a dangerous Costa Rica outfit who also took maximum points in their opener.
In a surprise result, they came from a goal down to beat Uruguay 3-1, hugely boosting their hopes of securing progression to the knockout stages for the first time since 1990.
"We should fear them a bit. You need a healthy fear against a team that surprised everyone with their victory over Uruguay," he said.
"Nobody thought they would get such a clear result against a very strong side.
"They'll be fired up after that win. If they had lost 4-0 then we could've underestimated them, but in this case we cannot possibly do that.
"I hope, and am convinced, that we can virtually secure qualification by beating Costa Rica. A victory would put a strong stamp on our ticket to the next round."
