The Spaniard has only been a Red Devil for just over 12 months after he joined the club from Premier League rivals Chelsea in a then club record deal worth around £37m.
Signed under David Moyes, Mata has struggled to cement himself in Louis van Gaal’s team, with the addition of £59.7m Argentine Angel di Maria and a shift in playing style having been factors.
And now Valencia are keen to offer him an escape route in the form of a £20m return to La Liga.
Los Che are no longer the financially stricken side they were when they sold the pass-master in 2011, with new owner Peter Lim having brought the cash reserves the club had been missing.
It’s understood that Mata is Valencia’s major target, with the big-hitters desperate to pull of a deal as they aim to keep pace with the likes of Barcelona, Real Madrid and Atletico Madrid.
The 26-year-old impressed in United’s 3-0 win over Spurs on Sunday, which was his first start for two months.