The rising star is one of Serie A's hottest prospects, and the Blues reportedly see him as the perfect replacement for Cesc Fabregas. Per Gazzetta dello Sport (h/t Goal's Chris Burton) Mancini praised the youngster but also pointed to the fact that he needs consistent playing time to continue his development:
"He has technique, quality, rarely loses the ball, is good in the air despite not being tall, never gives up and tends to push forward, but needs to also score a few more goals.
"Considering his age and the relative lack of Serie A experience, he has a strong grasp on his role already.
"Barella can set the example for the young Italian players out there who can give a little more to make that step up.
"He has enormous potential for growth and if he does leave Cagliari, he must be certain that he gets to play regularly.
"If he does go to a big club and is a first choice, then he can improve far more.
"However, if he risks spending half the season on the bench, he should stay put."
Cagliari have already ruled out a January exit, per Radiolina (h/t Football Italia), but that hasn't stopped the speculation. Matt Law of The Telegraph recently reported the Blues have a deal in place for the 21-year-old:
According to the Evening Standard's Simon Johnson a move for Leandro Paredes seems more likely, but Cagliari have seemingly found cover in the case of a departure:
Burton also linked the midfielder with Inter Milan, but most top clubs in Serie A have been rumoured as a destination at this point.
Napoli, in particular, are seen as a real possibility, and the Italian press believe the Partenopei are favourites, via ESPN FC's Andrew Cesare:
Barella is already a full Italy international and is closing in on 100 senior appearances for Cagliari despite his young age. A classic box-to-box player, he stands out for his versatility and well-rounded skill set, making him a perfect partner for a specialist passer or defender. Chelsea have elite options in both categories in Jorginho and N'Golo Kante.
He has already shown his ability to play next to Jorginho with the national team, where the two have quickly built some solid chemistry.
Cagliari seem determined not to part with their young star but are a relatively minor team from Sardinia with a limited budget. They sit seven points above the relegation zone and won't want to make any changes in January, but a summer move seems likely.