Sharpe - who is a Villa fan - reckons Grealish will be worth the £80m mooted for his sale, and he's also hailed the role of Villa assistant coach John Terry in the 24-year-old's rapid development.
“I think he's got Man United written all over him," Sharpe told Superstar Speakers.
“I think John Terry being at the club has changed his attitude a little bit towards how important he is in games, how valuable he is, how much he needs to not give the ball away cheaply and see himself as a top six player, a top European player.
"He has the ability, he goes past people with ease. He transitions defence to attack quite easily, creates and scores goals and I think he's got everything.
“I think in a good team, where someone can't single him out and there's other players there to mark and he ends up getting more room – I think he'll be sensational."