Tottenham are set to make their move for the Dutch left back who has been frustrated at his lack of games at Old Trafford with Patrice Evra the main man in that role.
United themselves have been heavily linked with a move for either Luke Shaw or Leighton Baines in this window and that would only push Buttner further down the pecking order.
Spurs are in the market for a full back after playing Jan Vertonghen, out of position, on the left side of their defence for the majority of this season with Danny Rose battling with injury.
Galatasaray are set to match any bid made by Spurs though and their financial firepower could attract Buttner who is hoping to be involved with the Netherlands squad at the World Cup in the summer despite not yet having an international cap.
United would be happy to let Buttner go but only for the right price and if they can sign one of their aforementioned targets.