Van Dijk joined Liverpool in a £75m deal from Southampton in January 2018.
“Virgil van Dijk was a big one for us,” he recalled on TalkSPORT. “We treated him in a different way and said, ‘You can’t go’. It didn’t work well for us.
“We didn’t (get him back on our side). Virgil was fantastic, in my opinion, he trained at 75 (percent) and played at 75 (percent) and was still the best player in the team, if not the league.
“He didn’t cause us any problems. He never said a single bad word to anyone, but he wanted to go, and it wasn’t effective for us to keep the player.
“We kept him until January. It wasn’t good for the squad or the environment, but to be clear, Virgil never said one negative word to anybody.
“We felt, at the time, we could get more if he stayed. He’d had a bad injury, I think he’d been out for six to nine months and we felt that he owed us, which is embarrassing now I think back to it.
“There was also some contact from Liverpool we didn’t love. At that time, probably a little more for the morals, he had already met Klopp before he told us.
“But in the end, he did a very good job for us and we sold him for a good price.”