Following up on a report from England, Gomez has received confirmation of United’s interest from Racic’s camp.
United have not yet made an offer for the Serbian under-21 international, who would cost around €30m.
Racic joined Valencia from Red Star Belgrade for €2.2m in June 2018 and has a €100m release clause.
Since his move to Spain, 22-year-old Rakic has been loaned out to Tenerife and most recently Famalicao.
His excellent form at the Portuguese club has led to interest from several clubs across Europe.
Racic is now back at Valencia and was a second half substitute for their season opener against Levante on Sunday.
Valencia know Racic is a player with a great future and are counting on him, but a good offer could see him leave the Mestalla.