The Slovakia international had to be substituted in the 66th minute as the Reds came from behind to win the second leg of the last-32 clash 3-1, so sealing a 4-1 aggregate success following last week's 1-0 victory at Anfield.
Boss Rafa Benitez confirmed after the match: "I think he maybe has a broken toe and I have to check with the doctor. We will have to check but I don't think it's good news for us."
Of his side's performance, Benitez added: "I think it was a difficult game and the pitch was terrible so we knew it could be tough and very demanding for the players.
"We conceded a goal and we then had to be calm and just keep playing our game.
"They have good deliveries from set-pieces and it was difficult to defend but then we scored our goal and scored again from a set-piece. At the end of the day we knew it could be like this tonight."
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