The Asian champions lost their first match 2-1 to Ivory Coast and were involved in a drab 0-0 stalemate with 10-man Greece in their second, leaving them not in control of their destiny.

Colombia have six points after two victories, with Ivory Coast second in Group C on three points. Japan and Greece both have a single point, though the Europeans have an inferior goal difference.

But the veteran Italian coach said despite his side's woes, he was feeling "pretty positive" ahead of their match against Colombia on Tuesday in Cuiaba.

Zaccheroni said he could not pin down a single reason why the Blue Samurai had failed to fire in Brazil, with only a single goal from Keisuke Honda to show for their efforts.

"We haven't had enough speed in our play and it's as though the players have been playing with the brakes on," he said. "The problem is probably mental.

"The result of the first game seems to have affected the following game. That's why now I have to work on that but I have full faith in our players and they have good capability to handle the situation."

Speaking at the team's training base in Itu, Zaccheroni said he had given the players the day off on Saturday so they could relax and clear their minds.

"I don't see any problems in their physical fitness," he said. "But I thought it would be better to give them a mental boost so they can be ready for the next game."

Zaccheroni, who succeeded Takeshi Okada after the Blue Samurai reached the last 16 at the World Cup in South Africa in 2010, led Japan to their fourth Asian Cup title the following year.

They reached Brazil in style, topping their Asian qualifying group ahead of Australia, but they have failed to impress so far, looking short on firepower.

"We know that overall our play over the past four years has been far better than how we have performed here and we all understand that," said Zaccheroni, whose managerial CV includes stints at AC Milan and Inter Milan.

"We're not satisfied with our performances so far," he added. "This team has given lots of joy and satisfaction in previous matches over the past four years so I'm hoping we can show that good part of our football against Colombia."