Japan coach Alberto Zaccheroni has called on his players to show more energy during their vital World Cup clash with Colombia on Tuesday.

The Japanese must beat Colombia and hope that the Ivory Coast drop points against Greece if they want to get out of Group C.

While admitting that his team has not performed to the best of their abilities so far at the tournament, Zaccheroni is hoping for an improvement tomorrow.

"We haven't had enough speed in our play and it's as though the players have been playing with the brakes on," he told reporters. "The problem is probably mental. We're not satisfied with our performances so far.

"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."

Zaccheroni claimed on Sunday that he was not sure whether he would continue in his role as Japan coach after the World Cup.