Zaniolo spent the second-half of last season on-loan at Villa Park from Galatasaray.
The Italy international told La Gazzetta dello Sport: "I will always be grateful to Douglas for the assist in the 1-1 draw against Sheffield United. My first goal in the Premier League, a header in the 97th minute... When it's official, I'll send him a message.
"We've always had a good relationship in Birmingham. A great signing for Juve, he's top. A complete, total midfielder. For me, he has so much quality that he could also be used further forward, as an attacking midfielder. He scores and makes others score, but he also recovers balls, gets involved and above all dictates the tempo of the play. He's worth all the money Juventus invested in him."
Zaniolo then concluded with 'advice' for Luiz: "If he did so well in the Premier League, he will repeat himself in Serie A. This is the only thing I would tell him. He is a great person and a leader. And I don't have a crystal ball but he seems perfect for Motta's ideas."