Germany international Mats Hummels is reportedly preparing to hand in a transfer request at Borussia Dortmund, placing Manchester United on red alert.
The central defender has long been linked with a move away from Dortmund, but has thus far remained at the club that he joined in 2009 from Bayern Munich.
According to Bild, the 26-year-old has now decided to seek pastures new and will force a move away from Dortmund in either January or next summer.
Man United are believed to be long-term admirers of the centre-back, who is fast closing on 300 Dortmund appearances.
Hummels, who only played twice for Bayern's first team between 1995 and 2009, has also racked up 44 appearances for Germany, scoring four times in the process.
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