Having already signed Jorginho from Napoli, while Hysaj is reported to be close to the Stamford Bridge side, Chelsea could make a third deal in under a year with the Partenopei. 

 

In fact, as reported by the English outlet The Times, Chelsea could soon make a move for Mertens, who would gladly reunite with his former coach in a new environment. However, despite the reports, it should be noted that Mertens himself has declared that he's happy at Napoli. 

 

Therefore, for a deal to take place, it would probably take some negotiating from Chelsea's side both with Napoli and Mertens, who's now played in Italy for five years.