Cagliari director Francesco Marroccu insists Davide Astori is not for sale.
Astori has been linked with AC Milan and Southampton.
"Davide Astori is a point of reference for the future," said Marroccu. "He is a player who we would not consider selling.
"Cagliari will start again from him. He represents us on the world stage and he is a certainty for us.
"And we have not forgotten when he rejected a move to Spartak Moscow last year in order to remain here.
"That gesture made us proud."