Southampton are reportedly willing to spend £13m in an attempt to shore up their leaky defence.
Only Aston Villa have conceded more Premier League goals than the Saints this season and manager Nigel Adkins is keen to address the issue during the January transfer window.
According to The Mirror, Southampton are prepared to offer £5m for Birmingham City goalkeeper Jack Butland and £8m for Cagliari centre-half Davide Astori.
Astori, 25, has been capped twice by Italy at senior international level.