Materazzi says he's a big fan of the Napoli midfielder, who has helped the Azzurri to the top of the Serie A table.
He told Il Mattino: "I love McTominay.
"Every time I see him play I continue to ask myself a question to which I have already given an answer: how did United let him slip away?
"Well, they are crazy. That's because he is a total player."