The Saints are being linked with a £12.5m move for the Italian international, who has now been capped seven times for his country.
Southampton have looked into the Italian market before, signing Gaston Ramirez from Bologna and Dani Osvaldo from AS Roma. Current goalkeeper Artur Boruc was with Serie A side Fiorentina prior to his switch to England.
The Saints were first linked with Astori in the 2012/13 season, when under the guidance of former manager Nigel Adkins. In the past, the Rossoblu, home to Astori for six years, had rejected Southampton's advances.
However, it is now thought that they will change their stance, after Club President Massimo Cellino revealed that both Davide Astori and Radja Nainggolan could leave the club if the right offer came in.
The club are looking to fund the necessary work to ensure that their Sant'Elia stadium can pass the required safety tests, after large parts of the ground were closed by the authorities for health and safety reasons.
Cagliari President Cellino went into a controversial rage at the authorities, claiming all of his star players, including Astori, are now up for sale:
"All the players are free to go; what the f*** are they still doing in this lousy stadium," the Cagliari supremo told reporters. "We play in a stadium worthy of Serie C."
Southampton appear reluctant to make moves in the January window however, with Mauricio Pochettino insisting that the club are satisfied that the club's academy could successfully plug any gaps that appear in the first team squad between now and the end of the season.
In any case, it is expected that Southampton will return for the twenty-seven year old Italian in the summer, as they seek a new partner for commanding Croatian defender Dejan Lovren, who has impressed the home crowd since his move from Olympique Lyonnais last summer.
image: © mischatuffield