Liverpool manager Juergen Klopp has decided to start the 24-year-old Karius, who played in Liverpool's 2-2 draw with Sevilla, the club said on their website (www.liverpoolfc.com), adding it "doesn't necessarily mean he is the club's first-choice stopper for all Champions League fixtures this season".
"It's all about performing," the website quoted Klopp as saying.
"That shouldn't be taken as me saying, 'You are not performing, you're out of the goal'. Everyone is allowed to make mistakes or whatever, but it's about performing in training and the games for all of our goalkeepers."
Klopp added that the squad's No. 1 goalkeeper was still Belgium's Simon Mignolet.
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Karius, speaking at a news conference in Moscow on Monday, said he was eager to use the Group E match to impress Klopp.
"I just see this as a chance when I get to play, to prove myself to the manager and use this Champions League as a chance for myself to show him I am ready for whatever competition," Karius said.
Klopp said earlier on Monday that his side, who have conceded 18 goals over 10 games in all competitions, were looking to boost their defence.
Karius said the team's defensive woes were due to their playing style.
"Of course we scored a lot of goals up front then sometimes we conceded a few. I don't think it's just down to the defence," he said.
"I think it's got to do with our style of play, our very offensive style. We sometimes take a few risks in defence."
(Reporting by Gabrielle Tétrault-Farber; Editing by Clare Fallon)
