Chelsea have made an official offer to sign Napoli defender Kalidou Koulibaly, TuttoMercatoWeb has revealed.
According to the article, the Blues offered £23million for the 24-year-old who is also a target for German side Bayern Munich.
But the Partenopei don't want to sell the player who wants to stay in Italy.
Chelsea have therefore shifted their focus on signing Roma centre-back Antonio Rudiger who is expected to leave the Giallorossi during the summer transfer window.
Rudiger, 23, is aware of Antonio Conte's interest and will take a decision over his future after the Euro 2016 Championship.