The Samurai Blue were swept aside by an emphatic Brazil attack, but the Italian is expecting his men to bounce back
Neymar's exquisite half-volley gave the Selecao early control of the proceedings, before Paulinho and Jo added to the tally to confirm their status as one of the tournament favourites.
The Japan coach believes there is much more to come from his side.
"We weren't able to demonstrate our abilities. We've only shown about 50% of what we can do," Zaccheroni lamented to reporters after the match.
"Brazil were very clever and played their emotional style on the pitch."
The 60-year-old nevertheless expressed his optimism over the next encounter: "We have time to think about the next match. We have to get back up and prepare for it."
Zaccheroni will be hoping to keep up the pace in Group A against compatriots Italy. The Azzurri will begin their Confederations Cup campaign against Mexico on Sunday.