The team admitted to panicking during their opening 2-1 loss to Ivory Coast, while fullback Yuto Nagatomo said they pressed the self-destruct button during Thursday's goalless Group C draw with 10-man Greece.
"They had every man behind the ball but we were kind of worried about their counter-attacks. It's difficult. But what it comes down to is that we didn't take our chances when we had them," Nagatomo told Japanese media.
"We spent all this time attacking and created a lot of chances but we couldn't win. It's such a waste. In football, you have to score goals to win, plain and simple. I think we self-destructed."
A win over already qualified Colombia in their final group match on Tuesday might not be enough to reach the knockout stages with Ivory Coast able to claim a last 16 spot for the first time with a win over Greece.
Japan coach Alberto Zaccheroni had called for his side to go on the offensive against the Greeks, who helped the Asian champions cause when they were reduced to 10-men shortly before halftime after skipper Kostas Katsouranis collected two yellow cards.
But despite almost 70 percent possession the Blue Samurai found the former European champions notoriously strong defence too tough to break down, with the Italian short of viable striking alternatives to call upon from the bench.
Striker Yuya Osako was pulled on the hour mark for playmaker Shinji Kagawa after misfiring for a second straight game, with out-of-form replacement Yoichiro Kakitani left to watch on from the bench.
The position has been a continued headache for Zaccheroni who has forged some brilliant attacking play in his four years in charge through the creative playmaking trio of Kagawa, ShinjiOkasaki and Keisuke Honda, who scored a spectacular opener against the Ivory Coast in Recifebefore fading away.
The Japanese smashed six past Jordan in qualifying and also impressed against top quality opposition as they scored three in a defeat by Italy last year and another trio in a win overBelgium.
But Honda and Kagawa have struggled for their club sides prior to the tournament and the issues have followed them to Brazil where goals have proved a problem for the first time under the Italian coach.
Outspoken forward Yoshito Okubo was guilty of missing a great opportunity to break the deadlock against the Greeks when he blasted over from close range in the 68th minute.
The Kawasaki Frontale man had been given a start ahead of misfiring Kagawa but was frustrated by the lack of urgency in the Asian's play.
"They parked the bus, big-time. But because they were so deep in their own half, there was plenty of space outside their box and we didn't take advantage of it," Okubo bemoaned.
"We were moving the ball around too much at the back and it was a waste of time. We needed to be crossing straight out of midfield and I was yelling at them to hurry things up, but they couldn't hear me.
"The more we pass it around, the more their defence has time to get set up and we should have spotted that."
