Southampton have signed Lazio defender Wesley Hoedt on a five-year deal.
The 23-year-old becomes Mauricio Pellegrino's third signing of the summer, following on from Poland defender Jan Bednarek and Juventus midfielder Mario Lemina, and Sky sources understand the deal could eventually be worth £17m.
Dutchman Hoedt, who began his career at AZ Alkmaar, moved to Lazio in 2015 and established himself as a leading defender in Serie A.
Hoedt made his senior Netherlands debut earlier this year and has since become a regular fixture in their squad.
Southampton vice chairman (Football) Les Reed said: "Wesley is one of the most promising young defenders in Europe and represents a significant addition to our squad. Having procured a Champions League finalist from one Italian club we have now added an Italian Supercoppa winner from another.
"We believe he has all the qualities to play a big part in our future, and we have worked hard to bring him to Southampton, with a number of other high-profile clubs interested in him.
"Finding a top quality central defender is difficult in the current environment and now we have six internationals in this position, both young and experienced.
"Finding a naturally left-footed player is even more difficult. We have been tracking central defenders on our target list for the past 12 months and Wesley has always been at the top of that list, so it was important to act when the opportunity came.
"Wesley has proven his talent through his performances for Lazio, as well as the Netherlands, and we believe he can develop even further here at Southampton, alongside his international teammate Virgil van Dijk, as well as the likes of Jack Stephens, Maya Yoshida, Jan Bednarek and Florin Gardos.
"With Wesley joining those players, we believe we have the right amount of quality, depth and flexibility at centre-back to help us achieve our aims this season."