Barcelona coach Ronald Koeman has spoken of working with Liverpool defender Virgil van Dijk.
Van Dijk's season appears over as he prepares to undergo knee surgery.
The Reds stopper was injured on Saturday after being clattered by Everton goalkeeper Jordan Pickford at Goodison Park. Having been forced from the pitch soon later, it was confirmed after the 2-2 draw that Van Dijk would require a knee operation.
Koeman first signed Van Dijk for Southampton from Celtic and later they were reunited when the Barca coach took charge of the Holland squad.
Reacting to news of Van Dijk's knee injury, Koeman commented on working with the defender and how he has improved from the player he signed from Celtic five years ago.
Koeman told Uefa via TMW of his former Holland defender: "It was great to work with Virgil because he is an open person, one who communicates.
"He likes to learn from everyone. He had to change his character because he was too lazy at times. Some say that his football is a bit arrogant. We worked a lot, but the credit goes to him.
"For me today he is one of the best defenders in the world."
Koeman was speaking before Barca's Champions League victory over Ferencvaros last night. The Catalans running out comfortable 5-1 winners.
Meanwhile, Liverpool kickoff their campaign - without Van Dijk - at Ajax on Wednesday night.
- updated October 21