Valencia and Atletico Madrid are both reportedly targeting the Spanish international, who has spent one season at Old Trafford.
It is currently unknown how much United would be willing to sell Herrera for, but the 25-year-old may find himself down the pecking order as the Red Devils have heavily upgraded their midfield.
They bought Memphis Depay before pulling off a double signing of Southampton midfielder Morgan Schneiderlin and Bayern Munich midfielder Bastian Schweinsteiger on the same day.
Despite doubts surrounding Herrera’s future with United, he put forth a solid 2014-15 season, with six goals in 26 Premier League appearances..
Although the Red Devils have rebuilt a midfield that struggled last season, Herrera would mark a relatively major loss as he showed promise in what could turn out to be a brief Premier League stint.
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