Italian source CalcioMercato (h/t Metro's Will Giles) claimed the Blues see 21-year-old Romagnoli as a replacement for outgoing skipper John Terry. But as the report also noted, Chelsea can expect to face strong competition for the young Rossoneri star.
Praise hasn't been in short supply for Romagnoli during recent seasons. Milan chief Sinisa Mihajlovic compared him to former Italy stalwart at the back, Alessandro Nesta, in 2014, according to EuroScout (via Yahoo Sport Italia, h/t ESPN FC's Michael Yokhin): "Alessio is like Alessandro Nesta, but more technical."
The player's greater technical aptitude is no doubt connected to his time spent at another position earlier in his career, a phase of his development Yokhin also detailed: "However, during his first few years in the academy, Romagnoli played in central midfield—which is why his technical skills are much better compared to the average centre-back."
Having a ball-playing central defender with pace would be a welcome boost for a Chelsea team that have aged at the back. Terry has seen his best days as a player, while 30-year-old Gary Cahill has always lacked pace as well as confidence in possession.
French youngster Kurt Zouma has the qualities a refreshed Blues defence needs, namely pace and aerial power. But the 21-year-old is currently recovering from a serious knee injury.
Still, Chelsea have already made plans for the future. The signing of Matt Miazga from New York Red Bulls is proof of that. But the Stamford Bridge club still needs a more ready-made young defender, one good enough to start next season.
Romagnoli has the potential and talent to be that player. But he isn't the only youthful defender on the Chelsea radar.
Blues Keen on Millwall's Teenage CB
The west London club are reportedly also keen on Millwall's 19-year-old central defender Christian Mbulu, according to the Sun (h/t Alex Harris of the Daily Star).
The reports detailed how Mbulu is already drawing comparisons to Manchester United centre-back and England international Chris Smalling:
Mbulu, 19, has been compared to Smalling after being snapped up from non-league Brentwood Town last summer.
Smalling was handed a professional contract by Fulham in 2008 when playing for Maidstone United before sealing his big-money move to Manchester United.
Mbulu recently spent time back on loan in the Ryman Premier League at Canvey Island.
While Mbulu's potential may not be doubted, there have to be questions about how far he is from the finished article. Even if he does eventually merit a quick transition to Millwall's first team, the jump from League One to the Premier League is still significant.
Smalling still needed three seasons to finally develop into a competent defender in England's top flight. With the pressure to compete at the top of the Premier League intense, Chelsea don't have that kind of time.
The Blues need a quick refresh of what was once a very strong defence. If the club really believes in Romagnoli's ability to help now, the Italian will be worth the money.