Coach Javier Aguirre and his Japan squad are dealing with some behind-the-scenes distractions that could complicate their bid for a record fifth Asian Cup title.

The defending champion will compete in Group D with Jordan, 2007 champion Iraq and the Palestinian team for the tournament which opens on Friday.

After victories in 1992, 2000, 2004 and 2011, another title would solidify Japan's place as the region's powerhouse.

But Japan is coming off a disappointing World Cup performance, where the team failed to advance beyond the group stage in Brazil, and the subsequent departure of head coach Alberto Zaccheroni.

This will be Aguirre's first major event at the helm, but the 56-year-old Mexican will arrive in Australia with some baggage.

According to Spanish media reports, authorities are investigating Aguirre and some 30 other people on suspicion of fixing a league game against Levante when he managed Zaragoza in May 2011.

Aguirre, who has denied the allegations, could be asked to appear in Spain if the complaint is accepted by a Valencia court and a full-scale investigation is opened.

Japan will be counting on Europe-based players Keisuke Honda, Shinji Kagawa and Shinji Okazaki to improve on the disappointing World Cup result.

Veteran striker Yoshito Okubo, who scored a J-League-leading 18 goals for Kawasaki Frontale this season, was not named to the 23-man roster.

Honda has scored seven goals for AC Milan this season and Okazaki has eight for Mainz, but Kagawa has struggled to regain the form that saw him score 21 goals for Borussia Dortmund from 2010-12. In 18 matches this season he has only two goals.

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