Mata has found himself to be a bit-part under Mourinho this season and showed his anger when frustrated against Southampton over the Christmas period.
The talented 25 year old knows that he needs to be playing regular football in order to make the Spain squad for the World Cup next summer and move back to La Liga was seen as a viable option.
Another player who could be on his way back to Spain is Michael Essien who was on loan at Real Madrid last season.
Mourinho has said that no bids have been lodged for either of his midfield stars although Kevin De Bruyne looks likely to leave.
“We have had no bids for Mata or Essien. We’ve had two for De Bruyne which we are analysing,” Mourinho confirmed.