Mata is under contract at Old Trafford until the end of this season.
Jose Mourinho has featured Mata in both of United’s Premier League fixtures this season.
But Mata has rejected the offer to stay around at United after this term.
Calciomeracto claim that the Spaniard has turned down a contract offer from United bosses and will look to return to Spain at the end of the season.
Mata started his career in the Real Madrid youth ranks but made his name at Valencia.