The Liverpool midfielder will face fellow Red Lucas Levia in the semi-final of the Olympic football tournament as Argentina play Brazil. The game is a chance for Mascherano to gain revenge after losing the 2007 Copa America.
"It will be a difficult match, but I think we'll play much better than them," he said.
"We will not make any mistake against them, or we may pay for that.
"We lost 0-3 in the Copa America final. Now there are some different players [in the Argentine team], but we still have four or five players who played that match in the team now.
"We'll watch their video later, and try to study them."