Liverpool midfielder Georginio Wijnaldum branded the challenge from Everton goalkeeper Jordan Pickford that injured Virgil van Dijk as "stupid" and called for the England number one to be punished.
Van Dijk looks set to miss the rest of the season after suffering cruciate ligament damage in a contentious 2-2 draw in the Merseyside derby on Saturday that also saw Everton forward Richarlison sent off for a wild lunge on Thiago Alcantara.
"Of course we are upset," said Wijnaldum at a pre-match press conference ahead of Wednesday's Champions League clash with Ajax.
"The way Pickford went in to the challenge was completely, in my opinion, stupid. I believe he didn't want to injure Virgil the way he injured him, but the way he took the tackle, he didn't care about what happened after the tackle.