FC Groningen chief Hans Nijland has confirmed Celtic defender Virgil van Dijk has signed with Southampton.
Van Dijk is a former Groningen player.
Nijland tweeted: "Just received a nice message from (Southampton manager) Ronald Koeman.
"We congratulate Virgil van Dijk wholeheartedly with his transfer to Southampton. A very nice and deserved transfer!
"The brothers Koeman, Tadic and now Virgil van Dijk. Beautiful!"
Saints are coughing up almost £12 million for Van Dijk.