article: Manchester United have put forward an opening £21.5million offer for Dortmund captain Mats Hummels, according to German newspaper Bild. The Germans value their captain at £35million but in United's favour he has had a relatively poor season occasionally clashing with supporters when results went against them earlier this season. Dortmund are keen to bring in Sami Khedira from Real Madrid as their new captain amid a summer of big changes following Jurgen Klopp's announcement that he will leave the club at the end of the season. Manchester United are reported to have put in a £21.5m bid for Dortmund defender Mats Hummels (left) Hummels (left) struggled early in the season for Dortmund and United hope to use that to their advantage . German paper Bild have reported the bid has been placed but Sportsmail understands the offer hasn't gone in yet. German World Cup winner Hummels is under contract with Dortmund until 2017 but earlier in the season admitted he would like to play abroad at some point in his career. He told Kicker: 'Some days I think I would definitely like to move abroad but then, other days, I think I don't fancy it at all,' he said when asked of United's interest. 'Basically, I think moving abroad would be good for my professional and personal well-being. Eventually, I'd like to leave the Bundesliga. 'I have had many conversations with the leaders of Dortmund, where I know I am a big part of the team, but I am yet to make a decision about my future. United also retain an interest in Hummels's Dortmund team-mate Ilkay Gundogan, who the club see as a potential successor to Michael Carrick. Ilkay Gundogan (right) is also a target for United as they look to revamp their squad in the summer . Dortmund want to bring in Real Madrid's Sami Khedira (right) as their new captain for next season .
highlights: Dortmund value defender Mats Hummels at £35million .
  Manchester United could take advantage of sea of change at Dortmund .
  Jurgen Klopp is leaving Dortmund and host of stars are expected to follow .
  Man Utd also identify Ilkay Gundogan as replacement for Michael Carrick .
  Man United fan provides Louis van Gaal with £300m transfer wish list .
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