Borussia Dortmund coach Jurgen Klopp has said he is still in regular contact with Shinji Kagawa, who has indicated that he could return to the Bundesliga club one day.
Japan international Kagawa left Dortmund for Manchester United last summer, but was not happy with some of his performances in his first Premier League season.
"We still keep in touch," Klopp told Bundesliga.de. "It's a bit difficult to speak to him directly, largely because his German hasn't dramatically improved while he's been in England. Talking to him on the phone isn't what you'd call a piece of cake."
Klopp added: "I often have a few words with Shinji's agent, Thomas Kroth, as well. Believe me, I'm always right in the picture about what the lad's up to."
Kagawa is not the only former Dortmund player Klopp keeps in touch with - AC Milan midfielder Kevin-Prince Boateng is also in regular contact with him.
"He is currently in pre-season and doesn't have much time - but we still chat regularly, and that won't change because he is like a mate," Boateng told eurosport.com.
Boateng spent six months on loan at Dortmund in Klopp's first year as coach. The club had wanted to sign him on a permanent deal but were unable to afford the €5 million transfer fee.
He has been linked with a return, but said: "I have never taken part in that speculation. I still wear black and red and have two years left on my contract, and that's why this question never arises for me."