Emotional Japan coach Alberto Zaccheroni said on Tuesday his team had failed to play to their potential during a disappointing FIFA World Cup™ campaign but refused to be drawn on his future.

Japan, needing an unlikely combination of results to qualify for the last 16 going into their final match against high-flying Colombia in Cuiaba, again came up short, losing 4-1.

The Samurai Blue impressed in the first half, dominating possession and equalised through a Shinji Okazaki header on the stroke of half-time, but they were undone by a vibrant Colombia in the second period.

It followed a 2-1 reverse to Côte d'Ivoire in their opening Group C game and a dour 0-0 draw against Greece, who eventually took the second qualifying slot after a last gasp 2-1 win over the Ivorians, alongside Colombia.

Zaccheroni said Japan had not managed to play the type of possession and pressing game they had produced so often over the past four years, though they had improved in their final group match.

"In general terms we all thought we would play a lot better," said the veteran Italian, who described the performances in Japan's first two matches as sub-par.

"As we showed today, especially in the first half, even against strong opposition I think we were able to show that when we play with intensity as we normally do, then we are able to generate opportunities to win."

Zaccheroni masterminded Japan's fourth AFC Asian Cup victory in 2011 and took them to the top of their Asian qualifying group but he said his side had fallen short both in last year's FIFA Confederations Cup in Brazil - where they lost all three matches - and at the World Cup.

"This team could have done a lot, lot more. I'm certain that here in Brazil I brought a great squad," he said.

The Italian described coaching Japan as an "incredible experience" but, looking visibly moved, said he would not discuss his future before first talking with Japanese football chiefs.

"Now we will go back to Japan and after that I will speak with the management and we will let you know whether or not I will stay," he said. "I think it's appropriate for this question to be discussed within the team first."