Borussia Dortmund coach Jürgen Klopp says Shinji Kagawa's peripheral role at Manchester United brings tears to his eyes.
Klopp brought Kagawa to Europe from Cerezo Osaka for just €350,000 in 2010 and the Japanese emerged into one of the most outstanding attackers on the continent in his two title-winning seasons with Dortmund.
United signed the 24-year-old for £17 million last summer however Sir Alex Ferguson failed to find a regular berth for him in the starting XI, which has left Klopp despairing for his former player.
"Shinji Kagawa is one of the best players in the world and he now plays 20 minutes at Manchester United – on the left wing! My heart breaks," Klopp told the Guardian. "Really, I have tears in my eyes.
"Central midfield is Shinji's best role. He's an offensive midfielder with one of the best noses for goal I ever saw. But for most Japanese people it means more to play for Man United than Dortmund. We cried for 20 minutes, in each others' arms, when he left."
Midfield has been a problem position at Old Trafford since Roy Keane's eight-year era as captain came to a turbulent end in 2005.
The last midfielder Ferguson bought was Owen Hargreaves in 2007, as he spent almost £200m on players in literally every other position in the following six years.
Kagawa was sidelined for over two months through injury this season, as the troubled Wayne Rooney started 31 games compared to Kagwa's 22.
The Japan international scored six goals in his debut season with United, including a classy hat-trick against Norwich City in March.