Reports: Man United make official Mats Hummels bid

Hummels is likely to join Man United in the summer. Credit: PA

Man United have tabled an opening offer of £21.5m for Mats Hummels, according to German publication Bild.

The German defender who is also a target for Liverpool is expected to follow Jurgen Klopp out of the door at Dortmund this summer.

Hummels has a contract at the club which runs until June 2017, and United will almost certainly be forced to increase their opening bid in order to secure his services.

World class central defender come at a premium and there is never a guarantee they will adjust to the rigours of English football.

Man City spent in excess of £30m on Eliaquim Mangala last year and the French international has struggled to adapt in the Premier League.