Kehl has warned that the Japan international Kagawa who is returning to the Westphalians for £6.3m will not be the player they remember.
The former Dortmund captain said: "Of course we've heard the latest speculation - we don't live on the moon - but we were focusing on the game (against Augsburg).
"Shinji was a very important factor in our side's successes in 2011 and 2012. He delivered some fantastic performances in Dortmund, but unfortunately he's not had such an easy time in Manchester.
"He's not been playing much and in particular his self-confidence is not going to be bubbling.
"If he were to join us, then he would need to be built back up again, and he would find the surroundings here where he would be welcomed wholeheartedly, both from the fans and from the team.
"He would get all the support he would need to be able to deliver his best performances again."
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