Colombia assured their place in the last 16 thanks to wins over Cote d'Ivoire and Greece and their coach admits to being disappointed by the Japanese performances so far
The South Americans go into Tuesday's match in Cuiaba assured of their place in the last 16 and sit atop Group C but the Asian champions need an unlikely set of results to progress.
"I think that Japan's expectations were much higher," said Pekerman. "If we consider how they prepared, their coach, their experience, we thought they'd have a better performance.
"But we're speaking about the past. We have to think about tomorrow. A team like Japan can recover and play a wonderful game because they need a victory."
Japan were beaten on matchday one by Cote d'Ivoire and drew 0-0 with Greece last time out, leaving them in third place in the group.
They need to beat Colombia and hope for Greece to take points from Cote d'Ivoire, but even that might not be enough, as a draw between the Greeks and the Elephants would leave Japan needing to beat Colombia by two clear goals.
Pekerman admitted he may be tempted into making changes for the third group match after taking maximum points from Greece and Cote d'Ivoire.
"We think those who played the longest should recover," he said. "There might be some changes. It would be good idea. Certain players could play very well.
"The team will face this match with this possibility and if we need to make changes we will. Everyone is very confident to play this game."