Manchester United are in negotiations to sign Jerome Boateng, the Bayern Munich defender whom Jose Mourinho has identified as a possible solution to what he regards as an acute lack of leadership and experience in his central defensive positions.

The problems perceived by Mourinho among his squad have focussed in the last week on the central defensive positions where Boateng, a 29-year-old who suffered a serious injury in April, is one option.

Bayern have started the negotiations at a steepling £50 million with the clubs in contact before their friendly at the Allianz Arena on Sunday night. The Germans also want a viable replacement before they are prepared to part with the player.

It would be a major investment in a footballer who will be 30 in September and who came close to missing the World Cup finals with a thigh injury that ended his club season for Bayern on April 21.

Mourinho’s stance all summer has been that he wanted additions at full-back and in midfield, with the pressure transferred to the club’s chief executive Ed Woodward and his key aide on transfers, Matt Judge.