While still aiming to Kalidou Koulibaly as a main target for their defensive roster, and having seemingly given up on Everton's John Stones (who's getting closer and closer to join Manchester City), Chelsea management, according to Sky Sports UK, have targeted Serbian international centre-back Nikola Maksimovic (24).
Currently on a deal with Torino until June 2020, the player is also tracked by Napoli themselves (Koulibaly's owning club), and the request set on him amounts now to €30/£25m.
Source: transfermarketweb.com