Stoke have one of the best defensive records in the Premier League at present, having kept nine clean sheets so far this season. That is thanks largely to Ryan Shawcross, who has put in some stirring, commanding defensive performances in recent weeks to keep Tony Pulis' side ticking over at the back. Shawcross has been at Man United once before. He signed as a fifteen year old in 2002 but Ferguson let him go for just £1million four years ago, and he has been with the Potter's ever since. However, a buy-back clause was inserted as part of the deal for Shawcross to join Stoke, which allows the Red Devil's first refusal if any clubs make an offer for the defender. United view Shawcross as the long-term replacement for Rio Ferdinand, however Stoke are set to offer the 25 year old a new 6-year deal, which would likely tie the defender down with the Potters for the rest of his playing career. Ferguson will have to move fast if he is to land his man. Source(s): Daily Mail