Castro has made a positive impression during his time under coach Vincenzo Italiano.

The 20-year-old Argentina international has been on Bologna's roster for a year, having joined from Velez Sarsfield.

According to sources, Chelsea is keeping a close eye on Castro's performance this season, with the possibility of signing him next year.

Castro's current market value is estimated to be between €50-70m by Bologna's intermediaries, while his current salary is relatively mo