The 32 year old defender only has six months remaining on his current deal, and although United plan to enter discussions over extending his stay at Old Trafford, the Serbian is keeping his options open.
"Vidic, given his contract situation, has several teams looking at him," his agent Silvano Martina told Radio Crc in Napoli.
"Vidic is a very good player and will have no trouble finding a new club. For the time being we are remaining calm. However, at the moment, I would rule out an extension with Manchester United."
United do not hold an option on the four-year deal Vidic signed in August 2010, and with the central defender's deal having moved into its final six months, a pre-contract agreement with another club could be agreed in readiness for a summer move.
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