The experienced shot-stopper has voiced his belief that a tough last-eight tie awaits and revealed his satisfaction at the win over Ecuador
The South American giants qualified for the first knockout stage by beating Ecuador 4-2 on Wednesday evening and will now meet Paraguay for the second time in the tournament, after the sides previously drew 2-2 in the group stage.
"We cannot relax. It is true that today Paraguay had a slightly weaker performance than they expected [a 3-3 draw against Venezuela], but they can improve," Julio Cesar said to reporters.
The Inter shot-stopper then went on to express his satisfaction with Brazil's win over Ecuador, although he confessed that he wasn't pleased with his individual performance.
"We knew it was a decisive match and I think the attitude from the squad was really important. It is good for the psychological aspect, because us, the more experienced players, are used to playing these kind of matches. It was good to walk out with a win.
"There are things that I can improve. The second goal was a bit harder than the first, but in both strikes I chose the wrong technical resource and did not have time to make the save."