That is the verdict of ESPN FC pundit and former England and Arsenal forward Paul Mariner.
AC Milan centre-back Romagnoli has been linked with a move to Manchester United in recent days.
United boss Jose Mourinho was desperate to bring in a central defender in the summer but deals for the likes of Harry Maguire, Toby Alderweireld and Jerome Boateng failed to materialise.
He now appears to have turned his attentions to Italy international Romagnoli.
Mariner is a fan of the 23-year-old but says United must sign another player who can play alongside him.
“I like him, I like him a lot,” the pundit said.
“But the problem is, when you have a player like Romagnoli going into United, who’s he going to play with?
“He needs somebody alongside him to solidify that defence. That’s what Manchester United have not got.
“They haven’t got two central defenders than can sure everything up.
“They’ve got the protection in front, but he needs to have somebody alongside him. So they need to get two.
“If they’re going to get him in, get another one, a more experienced player.
“If it was (Virgil) Van Dijk and him, thank you very much indeed, unbelievable. But it’s not.
“I say for United yes this is a fantastic move, he’s a good player. And for the kid, yeah I like it.”
Romagnoli came through the youth system at Roma before joining AC Milan in 2015.
He has made 119 appearances for the Serie A giants, scoring five goals.
The defender has eight caps for Italy since making his debut in 2016.