Brasilia: Japan coach Alberto Zaccheroni admitted Sunday he could be forced into a radical rethink to salvage his team`s World Cup dreams after an opening 2-1 loss to Ivory Coast.
The Asian champions took the lead in the Group C clash on Saturday through AC Milan midfielder Keisuke Honda in the 16th minute.
But the Africans hit back with Wilfried Bony and Gervinho scoring in the 64th and 66th minutes.
Japan will go on to face Greece in Natal on Friday before tackling Colombia in Cuiaba on June 24.
If the Asian giants are to progress, Zaccheroni believes his team need to improve in all departments.
"Our backs are against the wall. We need to recognise what went wrong and get back on the right track," said the veteran Italian coach.
"They didn`t do what was expected. I need now to think about what I have to do.
"I have to confess that I expected a lot more from my players."
Japan were out-fought by an Ivory Coast team who came to life when the imposing and experienced figure of Didier Drogba was summoned from the bench.
Two minutes later, the Africans were back on level terms.
Zaccheroni even hinted that Japan were undone by a fear of matching Ivory Coast in terms of physical confrontations.
"We started well with dynamism, but Ivory Coast were more and more intense," he said.
"Physically, they are very strong, more than we are capable of being.
"We lacked confidence in our passing and in our crosses. We needed to be more aggressive."
Japan also need to rethink their tactics, said Zaccheroni, after their inability to dominate possession handed the initiative to Ivory Coast who are looking to make the last 16 for the first time.
"Defensively, we were not effective and Ivory Coast won because they had more possession, we gave them too much space.
"They were allowed too much freedom to play and we lacked speed which is usually our big strength.
"I thought we could have won the game."