According to Todo Fichajes, the Red Devils duo will both be out of contract at the end of the season, and Sociedad are reportedly interested in signing both players. Cavani, in particular, could be a particularly useful signing for Sociedad, as Arsenal are reportedly interested in signing Alexander Isak.
Man Utd fans are unlikely to be too disappointed by the departures of Mata and Cavani, as neither player has been a regular at Old Trafford this season, and both players' prime years are likely to have passed them by now.
For a side like Sociedad, Cavani, on the other hand, may be an excellent short-term option to help them replace Isak, should the latter decide to join Arsenal.
Cavani may depart United this summer.
Mata, a former Chelsea and Valencia player, might also do well for the Basque side, with the former Spain international possibly attracted by a return to the country at this stage of his professional career.
In the meanwhile, Arsenal fans will hope that Isak is actually on his way out of the club, as he may be the ideal replacement for Pierre-Emerick Aubameyang, who left the club in January to join Barcelona.