Manchester United have reportedly prepared to make a bid for Antonio Rudiger if they are unable to complete the signing of Marcos Rojo.
The Sporting Lisbon defender has been pursued by the Premier League side throughout the summer, but the Portuguese club are thought to have asked United to increase their offer.
However, Sky Sports News reports that Louis van Gaal's side will turn their attention to the Stuttgart player if the Rojo negotiations break down.
Rojo is currently suspended by Sporting after refusing to train last week in a bid to force a move to Old Trafford.