The Red Devils have been heavily linked with a move for the Brazil international after he declared his desire to play in the Premier League next season.
Alves, whose Barcelona contract expires at the end of the season, has also been touted as a possible target for Liverpool.
Now, Gallardo has revealed that United have already agreed a preliminary deal to bring the 31-year-old full-back to Old Trafford next year.
“The player will leave Barcelona,” Gallardo is quoted as saying by Metro.
“He has signed a preliminary agreement with Manchester United.”
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