Blues boss Antonio Conte tried to bring Koulibaly to Stamford Bridge last summer.
But a deal failed to materialise with Napoli demanding £60million for the Senegal international.
Conte remains in the market for defensive reinforcements, with John Terry likely to leave Chelsea this summer.
Chelsea target Kalidou Koulibaly is open to a move to the Premier League
And Koulibaly has now put the Blues on alert by admitting he could leave Napoli.
"It would make me happy to come and play here, but I now I have to go to Napoli," Koulibaly told talkSPORT.
"In the future you never know.
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"Now I concentrate on my club and we will see next season what I have to do.
"I think I will stay in Napoli but you never know.
"I can't talk about it now. We will see."