Manchester United have joined the clubs showing interest in Schalke's talented midfielder Leon Goretzka. The 22-year-old Germany international is out of contract in the summer and has been offered lucrative new terms to stay at the Bundesliga side. However, Schalke face a tough task to convince him to remain in Germany with Europe's elite clubs clamouring to tempt him away. Arsenal, Juventus and Barcelona are already understood to have opened discussions with his representatives while Bayern Munich have also posted an interest. United manager Jose Mourinho wants to bolster his midfield with Michael Carrick coming to the end of his career and the likes of Henrikh Mkhitaryan and Juan Mata struggling to convince him they can provide the creative spark he craves.