Napoli president Aurelio De Laurentiis has confirmed that he knocked back a bid of £47m from Chelsea last summer for the signature of Kalidou Koulibaly.
The versatile 25-year-old defender was strongly linked with a switch to Stamford Bridge in the latter stages of the transfer window, before the Blues turned their attention to former player David Luiz on deadline day.
De Laurentiis has now explained the reason behind the big-money offer being rejected, citing a lack of reinforcements in Napoli's squad as a key factor why the Senegal international remained in place at Stadio San Paolo.
"Chelsea had offered €55m, but I told Conte that I could not give him up without first having a worthy substitute," he told beIN Sports.
"I will not sell the player unless [Maurizio] Sarri tells me: 'I have Tom, Dick and Harry who are reliable, you give up who you want.'"
In a separate interview, Koulibaly's agent hinted that the former Metz and Genk ace could be on the move at the end of the season if the right offer is made.