#3 Alessio Romagnoli (AC Milan)

Alessio Romagnoli is a 24-year-old centre-back who currently plays for AC Milan in Serie A. He has represented Italy's national team on eight occasions, having made his debut in October 2016.
Romagnoli spent much of his early career with Roma, progressing through their youth set-up before eventually being sold to Milan for £22m in 2015. For some players, the pressure of being transferred for that amount of money would break them down slightly, but that certainly hasn't happened in Romagnoli's case, if anything, he's gotten even better.
Romagnoli now has a market value of around £45m and with potential like his, United could possibly have to splash out double that to convince Milan to sell him. Whilst a club the size of Manchester United could afford this fee, it would still come with a great deal of risk for a player who has never played in the Premier League before.