The champions are expected to seal a potential club-record deal for the Spaniard before the end of the transfer window, and Savage thinkss that United need more players of the World Cup winner's calibre.
He told The Mirror: If United are going to finish in the top four, they will need another four or five signings of Mata's class – and there is just a week left in the transfer window.
"Fans who laughed at me after the summer window, when I said United would finish fifth, are not so vocal now.
"But just as I appeared to be a lone voice in the wilderness five months ago, I do hold out some hope for (manager) David Moyes in the transfer market if Mata proves to be the first of several new signings."
United are currently seventh in the Premier League.