According to Sky Italia's Gianluca Di Marzio, Southampton have lodged an £8.5m bid to sign Napoli centre back Kalidou Koulibaly this summer.
The Saints have been busy bringing in the likes of Maarten Stekelenburg, Cedric Soares, Steven Caulker, Jordy Clasie, Oriol Romeu and Juanmi, but manager Ronald Koeman is still on the lookout for new arrivals.
Having lost centre back Toby Alderweireld to Tottenham earlier this summer, there is still a need for a big replacement - even after signing Caulker on a season-long loan deal from Queens Park Rangers.
Now, Sky Italia's Di Marzio reports that Southampton have made a bid of €12m (£8.5m) for Napoli defender Kalidou Koulibaly.
The 24-year-old Frenchman, who joined Napoli from Genk just a year ago, impressed last season, but the arrival of Tottenham's Vlad Chiriches means his future is in doubt.
At 6ft 5in tall, Koulibaly is a giant of a defender, but also possesses great speed as well as versatility to play in defensive midfield, which could be appealing to Koeman.
Whether Napoli accept Southampton's bid remains to be seen, but Koulibaly's exceptional athletic traits make him an intriguing option for the Saints, who will be looking for a younger defender to partner veteran centre back Jose Fonte this summer.