BRASILIA, June 15 (Xinhua) -- Japan coach Alberto Zaccheroni said Saturday his team had played at just 50% of its capability during a 3-0 loss to Brazil here in the opening match of the Confederations Cup.

The 60-year-old Italian vowed the Blue Samurai would improve for their next fixture against Italy at Arena Pernambuco in Brazil's northeastern city of Recife on Wednesday.

"I think that today we haven't shown what we are capable of," Zaccheroni said after the match at Mane Garrincha stadium. "We were only at about 50% of our potential."

Zaccheroni also praised Luiz Felipe Scolari's team, saying the host nation had been spurred by the support of 70,000 mostly Brazilian fans.

"We have to give credit to Brazil's great performance. They played with emotion and the confidence that goes with playing at home in the first match of the tournament."

Japan guaranteed their place at the World Cup next year with a 1-1 draw against Australia earlier this month.