Virgil van Dijk has undergone successful knee surgery and will begin rehabilitation, Premier League champions Liverpool said on Friday.

The club would not say how long the 29-year-old central defender would be out.

Van Dijk, who was pivotal in both Liverpool’s Champions League success in 2019 and their title triumph last season, suffered cruciate ligament damage after a tackle from Everton goalkeeper Jordan Pickford earlier this month.

“Virgil van Dijk has undergone surgery on the knee ligament injury he sustained earlier this month,” read a club statement.

“The Liverpool defender’s planned operation took place in London and was conducted successfully.

“Van Dijk will now immediately focus on the beginning of his rehabilitation with the support of the Reds’ medical department.

“No time-frame has been placed on the Dutchman’s return to action.”

Liverpool manager Jurgen Klopp told his press conference on the eve of their Premier League home game with West Ham that Van Dijk was doing okay.

“This time (after a operation) is always unpleasant. He is good as good as can be,” said Klopp.

The 53-year-old German said it was time to move on even though Liverpool have spoken to referee chief Mike Riley about why VAR was not referred to.

Pickford’s challenge has been labelled as “stupid” by Liverpool midfielder Georginio Wijnaldum but Klopp drew a line under it.

“I don’t want to talk about this anymore. I would immediately if it would change anything but it doesn’t,” he said.

“I’m not sure the world is in a place right now where we have to keep this story going.

“Yes we still feel something about it, but nothing that will happen will change that. So I’ve nothing else to say.”

The Dutch international’s absence adds to Liverpool’s problems in central defence.

Joel Matip has missed the last three games injured and makeshift centreback Fabinho limped off in the first half of Tuesday’s Champions League match against Midtjylland with what is believed to be hamstring injury.

“Fab (Fabinho) is not in, he has a little injury,” said Klopp.

“He’s out for the weekend and slightly longer but all the others are in contention.”