Japanese star Shinji Kagawa said the challenge of playing in the English Premier League was behind his high-profile move to Manchester United.
United announced on Saturday it reached a deal for the 23-year-old Kagawa, who had one year left on his contract with two-time Bundesliga champion Borussia Dortmund but declined the club's extension offer.
''I considered many things but the most important was I wanted a challenge,'' Kagawa said after returning from Japan's 1-1 draw with Australia in a World Cup qualifier. ''When you look at the football scene (in England), it's the best league in the world.''
Kagawa joined Dortmund in 2010 from J-League side Osaka. In his two seasons in the Bundesliga, the attacking midfielder scored 21 goals in 49 appearances.
He missed the second half of his first season in Germany after breaking his metatarsal at the 2011 Asian Cup, but returned for the 2011-12 campaign and played a key part in helping Dortmund win the Bundesliga and German Cup double.
Kagawa will be the first Japanese to wear United's famous red shirt.
''I will have to work harder than ever,'' he said. ''I will have to take this step with the resolve to be the best player I can be.''
Players from Japan, however, have yet to make a real impact in the Premier League. Junichi Inamoto failed to start a league game during his time with Arsenal in the 2001-02 season, Kazayuki Toda played four games for Tottenham Hotspur in 2003 and teenage winger Ryo Miyaichi returned to Arsenal after being on loan with Bolton Wanderers.
Hidetoshi Nakata, a star of Serie A, had one season with Bolton in 2005-06 before retiring from the game.