Dortmund skipper Sebastian Kehl has added fuel to the rumours that Shinji Kagawa will return to the Bundesliga club by admitting he would be 'welcomed wholeheartedly' in Germany.
The Japan international left Dortmund for Manchester United in 2012 for an initial £12m fee, though he has found game time hard to come by at Old Trafford.
And Kehl says the 25-year-old would reproduce his best performances if he returned to the Bundesliga - thanks to the support of the Dortmund fans.
"Of course we've heard the latest speculation - we don't live on the moon - but we were focusing on the game [against Augsburg]," Kehl told reporters after Dortmund's 3-2 win on Friday.
"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."
Reports suggest Kagawa could rejoin the German club for a fee of £6.3 million.
The Japan midfielder appears out of favour under new boss Louis van Gaal, after the Dutchman admitted he did not meet his requirements playing in central midfield.