The rising number of Japanese footballers impressing in European leagues reflects the growing strength of the sport in the Asian region, Arsenal manager Arsene Wenger said Monday.

Wenger's Gunners are at German champions Borussia Dortmund in their opening Champions League match on Tuesday in Group F and Wenger says one of the names he is wary of is Dortmund's fleet-footed Japan star Shinji Kagawa.

The winger was in dazzling form for Dortmund last season with eight goals in 18 league games before a foot injury in the semi-final of the Asian Cup in January ruled him out of football for four months.

Kagawa scored twice in Japan's 3-0 trouncing of South Korea in Sapporo last month in a friendly when he made his return to the national team.

The 22-year-old is still working his way back to full fitness with Dortmund, but Wenger said the talents of Kagawa and Arsenal's Japanese teenager Ryo Miyaichi reflects the growing strength of Asian football.

"Kagawa is a very mobile player, he is very clever, very creative and is very quick in the box and that is why he is a proven goal-scorer," said Wenger.

"Miyaichi is not here, he is just coming back from injury and is playing for the reserves on Tuesday at Bolton.

"But both are very interesting players, I think it just shows what is happening all over the world at the moment, the push of Asian football towards the top quality.

"We saw it at the World Cup last year where teams like Japan did very well, along with North and South Korea. Asian football is pushing hard.

"We were in China before the start of the season and we saw some very good young players there too."

Japan striker Shinji Okazaki is also making a name for himself in the Bundesliga with some sharp finishing as the 25-year-old has already scored two goals in four German league games this season.