emanja Vidic has told Manchester United he doesn't want to quit the club this summer. The Serbian international is a target for Barcelona and Real Madrid with the Spanish giants prepared to pay £20m to lure him to La Liga. But despite having previously spoken of his difficulties settling in Manchester, Vidic has let it be known that he is happy at Old Trafford. That doesn't mean Sir Alex Ferguson won't still fancy cashing in on the 28-year-old, with the United manager already planning for the future with the signing of Fulham's Chris Smalling, who will join the club in the summer. Ferguson is also keeping strong tabs on Palermo's Danish international Simon Kjaer, who is also a target for Arsenal, Liverpool and Juventus. Having paid £7m to sign him from Spartak Moscow in 2006, Fergie stands to make a sizeable profit on Vidic if he decides to sell - if Barca and Real are forced into a bidding war. While the tough central defender has shown signs of returning to form in recent weeks, after missing large chunks of the season through injury, Ferguson will know that his value is only set to decrease as he gets older. And with Jonny Evans proving an able deputy over the past two seasons, the time could be right to cash in. United's hopes of a fourth successive title and a second Champions League success in three years have been severely dented by injuries to the old guard of Ferdinand and Vidic. Both have returned to fitness in time for the run-in, but having spent more than 12 months with a patchwork defence, Fergie is unlikely to want to go through the same again next season. And Vidic's determination to stay could fall on deaf ears if the right offer comes in. Should United keep Vidic? Have your say.