Georginio Wijnaldum said the tackles Liverpool were subject to in Saturday's Merseyside derby were "unacceptable" and said the players all had sleepless nights after seeing their talismanic defender Virgil Van Dijk was forced off with a potentially season-ending injury.

Van Dijk requires surgery after Jordan Pickford's knee-high tackle in the 11th minute of Saturday's game. Pickford's tackle went unpunished, but Van Dijk now faces months on the sidelines.

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Wijnaldum, 29, was talking ahead of Liverpool's Champions League opener in Amsterdam against Ajax on Wednesday, but the prematch news conference was dominated by questions over Van Dijk's long-term injury and also the injury Thiago Alcantara suffered thanks to Richarlison's late foul which led to him being shown a red card.

"We're still devastated," Wijnaldum said of Van Dijk's injury. "It's different than normal, the way it happened is really hard for us.

"I think everyone still has a bad feeling about it. When we were speaking with the lads after Saturday, I think none of the players slept because of what happened with Virgil and the way it happened. It's really hard one to take, and it was a hard one for the team."

Wijnaldum knows Van Dijk well as he's also his international teammate with the Netherlands.

"Of course we are upset -- the way Pickford went in on the challenge was, in my opinion, stupid," Wijnaldum continued. "I believe he didn't want to injure Virgil, but the way he took the tackle was basically he didn't care about what happened after the tackle.

"I think we had it a lot in the games against Everton. In my opinion they take it way too far in the games we play against them. We know it's a derby, and everyone wants to win the derby; sometimes you go over the top, but this was too much. It was not only his tackle but also Richarlison's tackle on Thiago was also a nasty one.

"That's what bothered me the most and the other players -- accidents can always happen in football, you can be unlucky with a tackle where you injure someone, but the way they were doing it was unacceptable. It makes it harder Pickford didn't get punished after seeing the videos."

Jurgen Klopp said the club has not yet received an answer to their request for a review into the VAR decisions from the Merseyside derby, and said the club is still coming to terms with Van Dijk's lengthy injury and the rough tackles they were subjected to.

"A couple of days ago, something happened that should not have happened in a football game. I see it similar to my players. Both challenges were difficult to accept, let me say it like this," Klopp said.

"It's not to change anymore. I spoke the day after, and it's really hard for us because Virgil's our boy. It's nothing to do with the quality of Virgil, yes, he's a world-class player and we will miss him, and injuries happen in football and very often in challenges. Very often both players try to play the ball, but it was not the case in these two challenges, and it makes it difficult to take.

"In the last four years we were the leader of the fair-play table -- we don't get anything for that, often enough it something where people make a joke about it. That means you can play football without these kinds of challenges.

"In this case the Michael Oliver didn't see it -- and he's an excellent referee -- but why he didn't see it, I don't understand as he had the best view. And VAR forgets the rules. But as a human being, it's not that I want an Everton player punished, but if you do something wrong, you have to deal with the consequences.

Klopp said Liverpool will also be without Joel Matip for Wednesday night's match against Ajax, meaning Fabinho is likely to step in at centre-back alongside Joe Gomez. And he also said he was not sure how long Thiago will be out for with the injury he picked up against Everton.

The Liverpool manager would also not be drawn on reports concerning a potential breakaway European tournament, called the "European Premier League," but turned attention to their opener against Ajax. He rubbished suggestions Ajax will be weaker for a summer where they lost key players Sergino Dest, Hakim Ziyech and Donny van de Beek and is instead expecting a firm test of his team's credentials on Wednesday.

"It's a sensational club with an outstanding philosophy with a world-class coach and world-class talent," Klopp said.