Doha (AFP) - Daichi Kamada was expected to be Japan's star man at the World Cup but the forward has flopped so far and he faces a huge test against Spain on Thursday.
Kamada has made a big impact since joining German side Eintracht Frankfurt, winning the Europa League last season and scoring 12 goals in all competitions so far this term.
The 26-year-old has found success at his first World Cup harder to come by, despite playing in Japan's stunning 2-1 opening win over Germany.
Kamada said his first-half performance in that game was "terrible", and would have been something that he "regretted for the rest of my life" had Japan not come back to claim the victory.
He was even more anonymous in his team's next outing, a dismal 1-0 defeat to Costa Rica that put the Blue Samurai's chances of reaching the last 16 in jeopardy.
A win over Spain in their final Group E match would clinch their place and Kamada is determined to make a timely return to form.
"I don't understand the way I've played these last two games," he said on Tuesday.
"I know I can play better than I have been -- make no mistake I can do it.There's one game left and I want to play better."
Kamada said he had racked his brain to find the cause of his slump but he had yet to come up with an answer.
"I had so many easy mistakes I couldn't believe it," he said of his performance against Costa Rica.
"It had nothing to do with the atmosphere in the stadium, me being in bad shape or carrying any kind of injury.I've been playing at the top level this season and that's not the problem.
"I've thought about it myself and to be honest, I have no idea."
No lack of confidence
Kamada has been in sparkling form for Eintracht this season after moving back from attack into midfield to accommodate forward Mario Goetze, who scored the goal that won the 2014 World Cup for Germany.
He has played as a forward for Japan at the World Cup so far but an injury to midfielder Wataru Endo means he could be an option for a more deep-lying role against Spain.
"Of course I can play in midfield and if I'm asked to, I will," he said.
"Whether I'm playing in midfield or behind the striker, it's not a problem for me."
The defeat to Costa Rica was met with fierce criticism in Japan, with coach Hajime Moriyasu's safety-first tactics taking the brunt of the fans' anger.
Moriyasu has insisted that his approach will remain the same regardless of results so far, and urged his players not to "ride the rollercoaster" of emotions.
Kamada said he was not struggling with confidence and backed himself to come good against Spain.
"Watch the next game and if I'm no good then I'll have to think about things," he said.
"I think I just the case that I haven't produced what I'm capable of in these last two games."